diff --git a/PROTOCOL.md b/PROTOCOL.md
index 2505b28..74bb2ba 100644
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@@ -3,14 +3,14 @@
 ## 包格式
 
 ```txt
-___________________________________________________________________________
-|             |           |                  |             |              |
-| sequence_id | operation | protocol_version | header_size | package_size |
-|_____________|___________|__________________|_____________|______________|
-|                                                                         |
-|                                  data                                   |
-|                                                                         |
-|_________________________________________________________________________|
+____________________________________________________________________________
+|              |             |                  |            |             |
+| package_size | header_size | protocol_version | operation  | sequence_id |
+|______________|_____________|__________________|____________|_____________|
+|                                                                          |
+|                                  data                                    |
+|                                                                          |
+|__________________________________________________________________________|
 ```
 
 包为 byte 数据,由头部和数据组成,字节序均为大端模式
@@ -19,7 +19,7 @@ ___________________________________________________________________________
 
 | 偏移量 | 长度 | 含义                      |
 | ------ | ---- | ------------------------- |
-| 0      | f    | 包总大小 package_size     |
+| 0      | 4    | 包总大小 package_size     |
 | 4      | 2    | 头部大小 header_size      |
 | 6      | 2    | 协议版本 protocol_version |
 | 8      | 4    | 操作码 operation          |