diff --git a/mindspore/core/utils/crypto.h b/mindspore/core/utils/crypto.h
index 686c2adcc92..a1e388154b9 100644
--- a/mindspore/core/utils/crypto.h
+++ b/mindspore/core/utils/crypto.h
@@ -23,10 +23,10 @@
 
 typedef unsigned char Byte;
 namespace mindspore {
-constexpr size_t MAX_BLOCK_SIZE = 512 * 1024 * 1024;  // Maximum ciphertext segment, units is Byte
-constexpr size_t RESERVED_BYTE_PER_BLOCK = 50;        // Reserved byte per block to save addition info
-constexpr unsigned int GCM_MAGIC_NUM = 0x7F3A5ED8;    // Magic number
-constexpr unsigned int CBC_MAGIC_NUM = 0x7F3A5ED9;    // Magic number
+constexpr size_t MAX_BLOCK_SIZE = 64 * 1024 * 1024;  // Maximum ciphertext segment, units is Byte
+constexpr size_t RESERVED_BYTE_PER_BLOCK = 50;       // Reserved byte per block to save addition info
+constexpr unsigned int GCM_MAGIC_NUM = 0x7F3A5ED8;   // Magic number
+constexpr unsigned int CBC_MAGIC_NUM = 0x7F3A5ED9;   // Magic number
 constexpr size_t Byte16 = 16;
 
 MS_CORE_API std::unique_ptr<Byte[]> Encrypt(size_t *encrypt_len, const Byte *plain_data, size_t plain_len,
diff --git a/mindspore/lite/src/common/decrypt.cc b/mindspore/lite/src/common/decrypt.cc
index 466efe70712..b440f88d53e 100644
--- a/mindspore/lite/src/common/decrypt.cc
+++ b/mindspore/lite/src/common/decrypt.cc
@@ -43,9 +43,9 @@ std::unique_ptr<Byte[]> Decrypt(const std::string &lib_path, size_t *, const Byt
 }
 #else
 namespace {
-constexpr size_t MAX_BLOCK_SIZE = 512 * 1024 * 1024;  // Maximum ciphertext segment, units is Byte
-constexpr size_t Byte16 = 16;                         // Byte16
-constexpr unsigned int MAGIC_NUM = 0x7F3A5ED8;        // Magic number
+constexpr size_t MAX_BLOCK_SIZE = 64 * 1024 * 1024;  // Maximum ciphertext segment, units is Byte
+constexpr size_t Byte16 = 16;                        // Byte16
+constexpr unsigned int MAGIC_NUM = 0x7F3A5ED8;       // Magic number
 DynamicLibraryLoader loader;
 }  // namespace
 int32_t ByteToInt(const Byte *byteArray, size_t length) {
@@ -253,7 +253,7 @@ std::unique_ptr<Byte[]> Decrypt(const std::string &lib_path, size_t *decrypt_len
   }
   std::vector<char> block_buf;
   std::vector<char> int_buf(sizeof(int32_t));
-  std::vector<Byte> decrypt_block_buf(MAX_BLOCK_SIZE);
+
   auto decrypt_data = std::make_unique<Byte[]>(data_size);
   int32_t decrypt_block_len;
 
@@ -303,13 +303,19 @@ std::unique_ptr<Byte[]> Decrypt(const std::string &lib_path, size_t *decrypt_len
     }
     block_buf.assign(model_data + offset, model_data + offset + block_size);
     offset += block_buf.size();
-    if (!(BlockDecrypt(decrypt_block_buf.data(), &decrypt_block_len, reinterpret_cast<Byte *>(block_buf.data()),
-                       block_buf.size(), key, static_cast<int32_t>(key_len), dec_mode, tag))) {
-      MS_LOG(ERROR) << "Failed to decrypt data, please check if dec_key or dec_mode is valid";
+    Byte *decrypt_block_buf = static_cast<Byte *>(malloc(MAX_BLOCK_SIZE * sizeof(Byte)));
+    if (decrypt_block_buf == nullptr) {
+      MS_LOG(ERROR) << "decrypt_block_buf is nullptr.";
       return nullptr;
     }
-    memcpy(decrypt_data.get() + *decrypt_len, decrypt_block_buf.data(), static_cast<size_t>(decrypt_block_len));
-
+    if (!(BlockDecrypt(decrypt_block_buf, &decrypt_block_len, reinterpret_cast<Byte *>(block_buf.data()),
+                       block_buf.size(), key, static_cast<int32_t>(key_len), dec_mode, tag))) {
+      MS_LOG(ERROR) << "Failed to decrypt data, please check if dec_key or dec_mode is valid";
+      free(decrypt_block_buf);
+      return nullptr;
+    }
+    memcpy(decrypt_data.get() + *decrypt_len, decrypt_block_buf, static_cast<size_t>(decrypt_block_len));
+    free(decrypt_block_buf);
     *decrypt_len += static_cast<size_t>(decrypt_block_len);
   }
   ret = loader.Close();
diff --git a/mindspore/python/mindspore/train/serialization.py b/mindspore/python/mindspore/train/serialization.py
index a962b769c52..cede450c49f 100644
--- a/mindspore/python/mindspore/train/serialization.py
+++ b/mindspore/python/mindspore/train/serialization.py
@@ -69,6 +69,7 @@ SLICE_SIZE = 512 * 1024
 PROTO_LIMIT_SIZE = 1024 * 1024 * 2
 TOTAL_SAVE = 1024 * 1024
 PARAMETER_SPLIT_SIZE = 1024 * 1024 * 1024
+ENCRYPT_BLOCK_SIZE = 64 * 1024
 
 
 def _special_process_par(par, new_par):
@@ -222,7 +223,7 @@ def _exec_save(ckpt_file_name, data_list, enc_key=None, enc_mode="AES-GCM"):
                         else:
                             plain_data += checkpoint_list.SerializeToString()
 
-                            max_block_size = SLICE_SIZE * 1024
+                            max_block_size = ENCRYPT_BLOCK_SIZE * 1024
                             while len(plain_data) >= max_block_size:
                                 cipher_data += _encrypt(plain_data[0: max_block_size], max_block_size, enc_key,
                                                         len(enc_key), enc_mode)