diff --git a/base/include/string_ex.h b/base/include/string_ex.h
index cf99110c3561048b2eec33507de2a2b1e8fa6196..2b70e5d2a50e523d1de41546bac8055a009bf538 100644
--- a/base/include/string_ex.h
+++ b/base/include/string_ex.h
@@ -242,6 +242,27 @@ std::string Str16ToStr8(const std::u16string& str16);
  * @return Returns an empty `std::u16string` object if the operation fails.
  */
 std::u16string Str8ToStr16(const std::string& str);
+
+/**
+ * @ingroup StringOperation
+ * @brief get the length of utf8 from utf16.
+ *
+ * @param str16 Indicates a `std::u16string` object.
+ * @return Returns -1 if the str16 is empty or the result is greater than INT MAX.
+ */
+int GetUtf16ToUtf8Length(const std::u16string& str16);
+
+/**
+ * @ingroup StringOperation
+ * @brief Converts a string from UTF-16 to UTF-8 encoded.
+ *
+ * @param str16 Indicates a `std::u16string` object.
+ * @param buffer Converted UTF-8 encoded buffer.
+ * @param bufferLen Buffer size.
+ * @return Returns the length of the converted UTF-8 encoding including the terminator '\0';
+ * Returns -1 if the operation fails.
+ */
+int Char16ToChar8(const std::u16string& str16, char *buffer, int bufferLen);
 #endif
 } // namespace OHOS
 
diff --git a/base/src/string_ex.cpp b/base/src/string_ex.cpp
index 0aa076b9b812939f336a3c04adc353ef84a4c8ec..46ac620af216fd9d600fee5063f32580d3d89c39 100644
--- a/base/src/string_ex.cpp
+++ b/base/src/string_ex.cpp
@@ -271,5 +271,37 @@ string Str16ToStr8(const u16string& str16)
 
     return str8Value;
 }
+
+int GetUtf16ToUtf8Length(const u16string& str16)
+{
+    size_t str16Len = str16.length();
+    if (str16Len == 0) {
+        return -1;
+    }
+    const char16_t *utf16Str = str16.c_str();
+    return Utf16ToUtf8Length(utf16Str, str16Len);
+}
+
+int Char16ToChar8(const u16string& str16, char *buffer, int bufferLen)
+{
+    if (buffer == nullptr || bufferLen <= 0) {
+        UTILS_LOGE("param is invalid!");
+        return -1;
+    }
+    size_t str16Len = str16.length();
+    if (str16Len == 0) {
+        UTILS_LOGE("str16 is empty!");
+        return -1;
+    }
+    const char16_t *utf16Str = str16.c_str();
+    int utf8Len = Utf16ToUtf8Length(utf16Str, str16Len);
+    if (utf8Len < 0 || (utf8Len + 1) > bufferLen) {
+        UTILS_LOGE("utf8buffer len:%{public}d, actual buffer len:%{public}d!", utf8Len + 1, bufferLen);
+        return -1;
+    }
+    StrncpyStr16ToStr8(utf16Str, str16Len, buffer, utf8Len + 1);
+    return utf8Len + 1;
+}
+
 #endif
 } // namespace OHOS
diff --git a/base/src/unicode_ex.h b/base/src/unicode_ex.h
index 6db9e5c0b30a24065ab20d6a3aff4f237a5f8474..3ce54ae945c888e3be1b9cab3ac7f7490da256c5 100644
--- a/base/src/unicode_ex.h
+++ b/base/src/unicode_ex.h
@@ -18,5 +18,9 @@
 namespace OHOS {
 bool String8ToString16(const std::string& str8, std::u16string& str16);
 bool String16ToString8(const std::u16string& str16, std::string& str8);
+extern "C" {
+    void StrncpyStr16ToStr8(const char16_t* utf16Str, size_t str16Len, char* utf8Str, size_t str8Len);
+    int Utf16ToUtf8Length(const char16_t* str16, size_t str16Len);
+}
 }
 #endif  // UTILS_BASE_LOG_H
diff --git a/base/test/unittest/common/utils_string_test.cpp b/base/test/unittest/common/utils_string_test.cpp
index e7ae3d8311bda879cb49e03fcbddf163981913d3..8b54675c233fa46a7d57071188cb756ec701bf67 100644
--- a/base/test/unittest/common/utils_string_test.cpp
+++ b/base/test/unittest/common/utils_string_test.cpp
@@ -16,6 +16,8 @@
 #include <gtest/gtest.h>
 #include "string_ex.h"
 #include <iostream>
+#include <securec.h>
+
 using namespace testing::ext;
 using namespace std;
 
@@ -531,6 +533,61 @@ HWTEST_F(UtilsStringTest, test_strcovert_04, TestSize.Level0)
     EXPECT_EQ(0, str8Result.compare(str8Value));
 }
 
+HWTEST_F(UtilsStringTest, test_getintstrcovert_01, TestSize.Level0)
+{
+    u16string str16Value = u"你好";
+    string str8Result = Str16ToStr8(str16Value);
+    int str8Length = str8Result.length();
+    int bufferLen = 255;
+    char buffer[bufferLen];
+    memset_s(buffer, sizeof(buffer), 0, sizeof(buffer));
+    int int8Result = Char16ToChar8(str16Value, buffer, bufferLen);
+
+    EXPECT_EQ(0, str8Result.compare(buffer));
+    EXPECT_EQ(str8Length + 1, int8Result);
+}
+
+HWTEST_F(UtilsStringTest, test_getintstrcovert_02, TestSize.Level0)
+{
+    u16string str16Value = u"某某技术有限公司";
+    string str8Result = Str16ToStr8(str16Value);
+    int str8Length = str8Result.length();
+    int bufferLen = 255;
+    char buffer[bufferLen];
+    memset_s(buffer, sizeof(buffer), 0, sizeof(buffer));
+    int int8Result = Char16ToChar8(str16Value, buffer, bufferLen);
+
+    EXPECT_EQ(0, str8Result.compare(buffer));
+    EXPECT_EQ(str8Length + 1, int8Result);
+}
+
+HWTEST_F(UtilsStringTest, test_getintstrcovert_03, TestSize.Level0)
+{
+    u16string str16Value = u"hello world!";
+    string str8Result = Str16ToStr8(str16Value);
+    int str8Length = str8Result.length();
+    int bufferLen = 255;
+    char buffer[bufferLen];
+    memset_s(buffer, sizeof(buffer), 0, sizeof(buffer));
+    int int8Result = Char16ToChar8(str16Value, buffer, bufferLen);
+
+    EXPECT_EQ(0, str8Result.compare(buffer));
+    EXPECT_EQ(str8Length + 1, int8Result);
+}
+
+HWTEST_F(UtilsStringTest, test_getintstrcovert_04, TestSize.Level0)
+{
+    u16string str16Value = u"1234567890!@#$%^&*().";
+    string str8Result = Str16ToStr8(str16Value);
+    int str8Length = str8Result.length();
+    int bufferLen = 255;
+    char buffer[bufferLen];
+    memset_s(buffer, sizeof(buffer), 0, sizeof(buffer));
+    int int8Result = Char16ToChar8(str16Value, buffer, bufferLen);
+
+    EXPECT_EQ(0, str8Result.compare(buffer));
+    EXPECT_EQ(str8Length + 1, int8Result);
+}
 
 HWTEST_F(UtilsStringTest, test_getsubstr_01, TestSize.Level0)
 {