diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/instances/SchematicsPage.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/instances/SchematicsPage.java
index b7e21447c3..d0f7b4a047 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/instances/SchematicsPage.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/instances/SchematicsPage.java
@@ -41,6 +41,7 @@
 import org.jackhuang.hmcl.task.Task;
 import org.jackhuang.hmcl.ui.*;
 import org.jackhuang.hmcl.ui.construct.*;
+import org.jackhuang.hmcl.util.FileNameSet;
 import org.jackhuang.hmcl.util.Lang;
 import org.jackhuang.hmcl.util.StringUtils;
 import org.jackhuang.hmcl.util.i18n.I18n;
@@ -161,10 +162,20 @@ public void onCreateDirectory() {
             return;
 
         Path parent = currentDirectory.path;
+
+        FileNameSet existingPaths;
+        try {
+            existingPaths = FileNameSet.list(parent, null);
+        } catch (Exception e) {
+            LOG.warning("Failed to list folders in " + parent, e);
+            existingPaths = new FileNameSet(false);
+        }
+
         Controllers.prompt(
                 i18n("schematics.create_directory.prompt"),
                 (result, handler) -> {
                     Path targetDir = parent.resolve(result);
+
                     if (Files.exists(targetDir)) {
                         handler.reject(i18n("schematics.create_directory.failed.already_exists"));
                         return;
@@ -178,7 +189,11 @@ public void onCreateDirectory() {
                         LOG.warning("Failed to create directory: " + targetDir, e);
                         handler.reject(i18n("schematics.create_directory.failed", targetDir));
                     }
-                }, "", new RequiredValidator(), new Validator(i18n("schematics.create_directory.failed.invalid_name"), FileUtils::isNameValid));
+                },
+                "",
+                new RequiredValidator(),
+                new Validator(i18n("schematics.create_directory.failed.invalid_name"), FileUtils::isNameValid),
+                new Validator(i18n("schematics.create_directory.failed.already_exists"), existingPaths::notContains));
     }
 
     private DirItem loadAll(Path dir, @Nullable DirItem parent) {
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/FileNameSet.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/FileNameSet.java
new file mode 100644
index 0000000000..d8ffaabec8
--- /dev/null
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/FileNameSet.java
@@ -0,0 +1,96 @@
+/*
+ * Hello Minecraft! Launcher
+ * Copyright (C) 2026 huangyuhui <huanghongxun2008@126.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.jackhuang.hmcl.util;
+
+import org.jackhuang.hmcl.util.platform.OperatingSystem;
+import org.jetbrains.annotations.NotNullByDefault;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.IOException;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashSet;
+import java.util.Locale;
+import java.util.function.Predicate;
+
+/// @author Glavo
+@NotNullByDefault
+public final class FileNameSet {
+    public static FileNameSet list(Path directory, @Nullable Predicate<? super Path> predicate) throws IOException {
+        try (var list = Files.list(directory)) {
+            boolean caseSensitive = OperatingSystem.CURRENT_OS != OperatingSystem.WINDOWS
+                    || directory.getFileSystem() != FileSystems.getDefault();
+            var set = new FileNameSet(caseSensitive);
+
+            list.forEachOrdered(path -> {
+                if (predicate == null || predicate.test(path)) {
+                    set.add(path.getFileName().toString());
+                }
+            });
+
+            return set;
+        }
+    }
+
+    private final boolean caseSensitive;
+
+    private final HashSet<String> set = new HashSet<>();
+
+    public FileNameSet(boolean caseSensitive) {
+        this.caseSensitive = caseSensitive;
+    }
+
+    public boolean add(String name) {
+        if (caseSensitive) {
+            return set.add(name);
+        } else {
+            return set.add(name.toLowerCase(Locale.ROOT));
+        }
+    }
+
+    public boolean contains(String name) {
+        if (set.isEmpty())
+            return false;
+
+        if (caseSensitive) {
+            return set.contains(name);
+        } else {
+            return set.contains(name.toLowerCase(Locale.ROOT));
+        }
+    }
+
+    public boolean notContains(String name) {
+        return !contains(name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Boolean.hashCode(caseSensitive) ^ set.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return this == obj || obj instanceof FileNameSet that && this.caseSensitive == that.caseSensitive && this.set.equals(that.set);
+    }
+
+    @Override
+    public String toString() {
+        return set.toString();
+    }
+}