diff --git a/hutool-core/src/main/java/cn/hutool/core/io/FileUtil.java b/hutool-core/src/main/java/cn/hutool/core/io/FileUtil.java
index ab9b68894..35663d8ee 100755
--- a/hutool-core/src/main/java/cn/hutool/core/io/FileUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/io/FileUtil.java
@@ -3459,25 +3459,13 @@ public class FileUtil extends PathUtil {
 	 */
 	public static File checkSlip(File parentFile, File file) throws IllegalArgumentException {
 		if (null != parentFile && null != file) {
-			if (false == startsWith(parentFile, file)) {
+			if (false == isSub(parentFile, file)) {
 				throw new IllegalArgumentException("New file is outside of the parent dir: " + file.getName());
 			}
 		}
 		return file;
 	}
 
-	/**
-	 * 检查父文件是否为文件真正的父目录
-	 *
-	 * @param parentFile 父目录
-	 * @param file       文件
-	 * @return 是否为文件真正的父目录
-	 */
-	public static boolean startsWith(final File parentFile, final File file) {
-		return PathUtil.toAbsNormal(parentFile.toPath())
-			.startsWith(PathUtil.toAbsNormal(file.toPath()));
-	}
-
 	/**
 	 * 根据文件扩展名获得MimeType
 	 *
diff --git a/hutool-core/src/test/java/cn/hutool/core/io/FileUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/io/FileUtilTest.java
index a0f2a197f..478501e7c 100644
--- a/hutool-core/src/test/java/cn/hutool/core/io/FileUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/io/FileUtilTest.java
@@ -20,8 +20,14 @@ import java.util.List;
  */
 public class FileUtilTest {
 
+	@Test
+	public void fileTest1() {
+		final File file = FileUtil.file("d:/aaa", "bbb");
+		Assert.assertNotNull(file);
+	}
+
 	@Test(expected = IllegalArgumentException.class)
-	public void fileTest() {
+	public void fileTest2() {
 		final File file = FileUtil.file("d:/aaa", "bbb");
 		Assert.assertNotNull(file);