diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Config.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Config.java
index 89632bd7f30e..5e788a35a321 100755
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Config.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Config.java
@@ -168,7 +168,8 @@ public static class Logging {
         public static String FILE_NAME = "skywalking-api.log";
 
         /**
-         * Log files directory. Default is blank string, means, use "system.out" to output logs.
+         * Log files directory. Default is blank string, means, use "{theSkywalkingAgentJarDir}/logs  " to output logs. 
+         * {theSkywalkingAgentJarDir} is the directory where the skywalking agent jar file is located.
          *
          * Ref to {@link WriterFactory#getLogWriter()}
          */
diff --git a/docs/en/setup/service-agent/java-agent/README.md b/docs/en/setup/service-agent/java-agent/README.md
index b5337056c1c5..bf80d5f39cdc 100755
--- a/docs/en/setup/service-agent/java-agent/README.md
+++ b/docs/en/setup/service-agent/java-agent/README.md
@@ -93,7 +93,7 @@ property key | Description | Default |
 `logging.level`|The log level. Default is debug.|`DEBUG`|
 `logging.file_name`|Log file name.|`skywalking-api.log`|
 `logging.output`| Log output. Default is FILE. Use CONSOLE means output to stdout. |`FILE`|
-`logging.dir`|Log files directory. Default is blank string, means, use "system.out" to output logs.|`""`|
+`logging.dir`|Log files directory. Default is blank string, means, use "{theSkywalkingAgentJarDir}/logs  " to output logs. {theSkywalkingAgentJarDir} is the directory where the skywalking agent jar file is located |`""`|
 `logging.pattern `|logging format. There are all conversion specifiers: <br>&nbsp;&nbsp;* `%level` means log level. <br>&nbsp;&nbsp;*  `%timestamp` means now of time with format `yyyy-MM-dd HH:mm:ss:SSS`.<br>&nbsp;&nbsp;*   `%thread` means name of current thread.<br>&nbsp;&nbsp;*   `%msg` means some message which user logged. <br>&nbsp;&nbsp;*  `%class` means SimpleName of TargetClass. <br>&nbsp;&nbsp;*  `%throwable` means a throwable which user called. <br>&nbsp;&nbsp;*  `%agent_name` means `agent.service_name`  |`%level %timestamp %thread %class : %msg %throwable`|
 `logging.max_file_size`|The max size of log file. If the size is bigger than this, archive the current file, and write into a new file.|`300 * 1024 * 1024`|
 `logging.max_history_files`|The max history log files. When rollover happened, if log files exceed this number,then the oldest file will be delete. Negative or zero means off, by default.|`-1`|