Relay protection code when B has a very important role in smart substation clock management role, the paper analyzes the application of relay protection in the B code time, combined CMC256-6 tester and ZH-503 time synchronization system, about a comprehensive testing program of relay protection IRIG-B time code on. Through CMC256-6 tester simulates B code pulse waveform playback device to the protective device to achieve B code, during playback by modifying the pulse of each code element B code to simulate a variety of abnormal B code, comprehensive verification code time protection device B processing logic, and for a long time B code pager to protection by ZH-503 time synchronization system, verify protection device B code when dealing with stability and reliability. The program for testing and development of relay protection B code when a certain reference value.