diff --git a/AIStudyApp/AIStudyApp/Core/Models/APIModels.swift b/AIStudyApp/AIStudyApp/Core/Models/APIModels.swift
index 9b17be8..2977484 100644
--- a/AIStudyApp/AIStudyApp/Core/Models/APIModels.swift
+++ b/AIStudyApp/AIStudyApp/Core/Models/APIModels.swift
@@ -174,6 +174,12 @@ struct KnowledgeBase: Codable, Identifiable {
 struct CreateKnowledgeBaseRequest: Codable {
     let title: String
     let description: String?
+    let coverKey: String?
+}
+
+struct KnowledgeBaseCoverUploadResult {
+    let fileId: String
+    let objectKey: String
 }
 
 // MARK: - Knowledge Items (matches Prisma KnowledgeItem model)
diff --git a/AIStudyApp/AIStudyApp/Core/Services/APIService.swift b/AIStudyApp/AIStudyApp/Core/Services/APIService.swift
index 0a9d012..d3dd331 100644
--- a/AIStudyApp/AIStudyApp/Core/Services/APIService.swift
+++ b/AIStudyApp/AIStudyApp/Core/Services/APIService.swift
@@ -85,8 +85,8 @@ class KnowledgeBaseService {
         ])
     }
 
-    func create(title: String, description: String?) async throws -> KnowledgeBase {
-        let body = CreateKnowledgeBaseRequest(title: title, description: description)
+    func create(title: String, description: String?, coverKey: String? = nil) async throws -> KnowledgeBase {
+        let body = CreateKnowledgeBaseRequest(title: title, description: description, coverKey: coverKey)
         return try await client.request("/knowledge-bases", method: "POST", body: body)
     }
 
diff --git a/AIStudyApp/AIStudyApp/Core/Services/FileUploadService.swift b/AIStudyApp/AIStudyApp/Core/Services/FileUploadService.swift
index bc05c4c..c010470 100644
--- a/AIStudyApp/AIStudyApp/Core/Services/FileUploadService.swift
+++ b/AIStudyApp/AIStudyApp/Core/Services/FileUploadService.swift
@@ -6,12 +6,44 @@ class FileUploadService {
     static let shared = FileUploadService()
     private let client = APIClient.shared
 
-    /// 上传图片到 COS 并返回文件 ID
-    func uploadImage(_ image: UIImage, filename: String = "avatar.jpg") async throws -> String {
-        guard let imageData = image.jpegData(compressionQuality: 0.7) else {
+    /// 上传图片到 COS 并返回文件 ID + objectKey
+    func uploadImageWithKey(_ image: UIImage, filename: String = "cover.jpg") async throws -> (fileId: String, objectKey: String) {
+        guard let imageData = image.jpegData(compressionQuality: 0.75) else {
             throw FileUploadError.compressFailed
         }
-        return try await uploadData(imageData, filename: filename, mimeType: "image/jpeg")
+        return try await uploadDataWithKey(imageData, filename: filename, mimeType: "image/jpeg")
+    }
+
+    /// 上传图片到 COS 并返回文件 ID
+    func uploadImage(_ image: UIImage, filename: String = "avatar.jpg") async throws -> String {
+        let result = try await uploadImageWithKey(image, filename: filename)
+        return result.fileId
+    }
+
+    /// 上传原始数据到 COS 并返回 fileId + objectKey
+    func uploadDataWithKey(_ data: Data, filename: String, mimeType: String) async throws -> (fileId: String, objectKey: String) {
+        let urlReq = FileUploadUrlRequest(
+            filename: filename, mimeType: mimeType, sizeBytes: data.count
+        )
+        let urlResp: FileUploadUrlResponse = try await client.request(
+            "/files/upload-url", method: "POST", body: urlReq
+        )
+
+        var request = URLRequest(url: URL(string: urlResp.uploadUrl)!)
+        request.httpMethod = "PUT"
+        request.setValue(mimeType, forHTTPHeaderField: "Content-Type")
+        request.httpBody = data
+        let (_, response) = try await URLSession.shared.data(for: request)
+        guard let httpResp = response as? HTTPURLResponse, httpResp.statusCode == 200 else {
+            throw FileUploadError.uploadFailed
+        }
+
+        let confirmResp: FileConfirmUploadResponse = try await client.request(
+            "/files/complete", method: "POST",
+            body: FileConfirmUploadRequest(objectKey: urlResp.objectKey, checksum: nil)
+        )
+
+        return (fileId: confirmResp.id, objectKey: urlResp.objectKey)
     }
 
     /// 上传原始数据到 COS 并返回文件 ID
diff --git a/AIStudyApp/AIStudyApp/Features/Library/LibrarySubpages.swift b/AIStudyApp/AIStudyApp/Features/Library/LibrarySubpages.swift
index 73baafa..21431b1 100644
--- a/AIStudyApp/AIStudyApp/Features/Library/LibrarySubpages.swift
+++ b/AIStudyApp/AIStudyApp/Features/Library/LibrarySubpages.swift
@@ -4,17 +4,42 @@ import UniformTypeIdentifiers
 
 struct CreateLibraryPage: View {
     @Environment(\.dismiss) private var dismiss
-    @State private var name = ""; @State private var desc = ""; @State private var isCreating = false
+    @State private var name = ""; @State private var desc = ""
+    @State private var isCreating = false; @State private var isUploadingCover = false
+    @State private var coverKey: String?; @State private var coverImage: UIImage?
+    @State private var showCoverPicker = false; @State private var coverPhotoItem: PhotosPickerItem?
     var body: some View {
         ZStack { Color.zxBg0.ignoresSafeArea(); VStack(spacing: 0) {
             ScrollView { VStack(spacing: 20) {
+                // 封面
+                VStack(alignment: .leading, spacing: 8) {
+                    Text("封面图（可选，3:2）").font(.system(size: 12, weight: .semibold)).foregroundColor(Color.zxF035)
+                    Button { showCoverPicker = true } label: {
+                        ZStack {
+                            RoundedRectangle(cornerRadius: 14).fill(Color.zxFill004)
+                                .overlay(RoundedRectangle(cornerRadius: 14).stroke(style: StrokeStyle(lineWidth: 1.5, dash: [6, 4])).foregroundColor(Color.zxBorder01))
+                                .frame(height: 160)
+                            if let img = coverImage {
+                                Image(uiImage: img).resizable().scaledToFill().frame(height: 160).clipShape(RoundedRectangle(cornerRadius: 14))
+                            } else {
+                                VStack(spacing: 8) {
+                                    Image(systemName: "photo.badge.plus").font(.system(size: 28)).foregroundColor(Color.zxF04)
+                                    Text("点击上传封面图").font(.system(size: 13)).foregroundColor(Color.zxF04)
+                                }
+                            }
+                            if isUploadingCover { RoundedRectangle(cornerRadius: 14).fill(Color.black.opacity(0.4)).frame(height: 160); ProgressView().tint(.white) }
+                        }
+                    }.disabled(isUploadingCover)
+                }
                 VStack(alignment: .leading, spacing: 8) { Text("知识库名称").font(.system(size: 12, weight: .semibold)).foregroundColor(Color.zxF035); TextField("例如：机器学习", text: $name).font(.system(size: 15)).tint(Color.zxPurple).padding(.horizontal, 16).frame(height: 52).background(Color.zxFill004).clipShape(RoundedRectangle(cornerRadius: 14)).overlay(RoundedRectangle(cornerRadius: 14).stroke(Color.zxBorder008, lineWidth: 1)) }
                 VStack(alignment: .leading, spacing: 8) { Text("描述（可选）").font(.system(size: 12, weight: .semibold)).foregroundColor(Color.zxF035); TextField("简单描述这个知识库的内容", text: $desc).font(.system(size: 15)).tint(Color.zxPurple).padding(.horizontal, 16).frame(height: 52).background(Color.zxFill004).clipShape(RoundedRectangle(cornerRadius: 14)).overlay(RoundedRectangle(cornerRadius: 14).stroke(Color.zxBorder008, lineWidth: 1)) }
                 Button {
                     guard !name.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty else { return }
                     isCreating = true
                     Task {
-                        let kb = try? await KnowledgeBaseService.shared.create(title: name, description: desc.isEmpty ? nil : desc)
+                        let kb = try? await KnowledgeBaseService.shared.create(
+                            title: name, description: desc.isEmpty ? nil : desc, coverKey: coverKey
+                        )
                         await MainActor.run {
                             isCreating = false
                             if kb != nil {
@@ -36,7 +61,35 @@ struct CreateLibraryPage: View {
                 }
                 .disabled(isCreating || name.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty)
             }.padding(.horizontal, 20).padding(.top, 20) }.scrollIndicators(.hidden) }
-        }.navigationBarTitleDisplayMode(.inline).toolbarBackground(.hidden, for: .navigationBar).animatedTabBarHide()}
+        }.navigationBarTitleDisplayMode(.inline).toolbarBackground(.hidden, for: .navigationBar).animatedTabBarHide()
+        .photosPicker(isPresented: $showCoverPicker, selection: $coverPhotoItem, matching: .images)
+        .onChange(of: coverPhotoItem) { _, item in
+            guard let item else { return }
+            Task { await uploadCover(item) }
+        }}
+    }
+
+    private func uploadCover(_ item: PhotosPickerItem) async {
+        isUploadingCover = true
+        defer { isUploadingCover = false; coverPhotoItem = nil }
+        guard let data = try? await item.loadTransferable(type: Data.self),
+              let image = UIImage(data: data) else { return }
+        let resized = resizeCoverImage(image, tw: 600, th: 400)
+        do {
+            let r = try await FileUploadService.shared.uploadImageWithKey(resized, filename: "cover_\(Int(Date().timeIntervalSince1970)).jpg")
+            coverKey = r.objectKey; coverImage = resized
+        } catch { ZXToastManager.shared.error("封面上传失败") }
+    }
+
+    private func resizeCoverImage(_ image: UIImage, tw: CGFloat, th: CGFloat) -> UIImage {
+        let tr = tw / th; let ir = image.size.width / image.size.height
+        let rect: CGRect
+        if ir > tr { let nw = image.size.height * tr; rect = CGRect(x: (image.size.width - nw)/2, y: 0, width: nw, height: image.size.height) }
+        else { let nh = image.size.width / tr; rect = CGRect(x: 0, y: (image.size.height - nh)/2, width: image.size.width, height: nh) }
+        guard let cg = image.cgImage?.cropping(to: rect) else { return image }
+        let r = UIGraphicsImageRenderer(size: CGSize(width: tw, height: th))
+        return r.image { _ in UIImage(cgImage: cg).draw(in: CGRect(origin: .zero, size: CGSize(width: tw, height: th))) }
+    }
 }
 
 struct LibraryDetailPage: View {