In view of the disadvantages of the current intelligent substation optical fiber link measurement, such as low efficiency, unable to real-time monitoring and self diagnosis, this paper designs an intelligent diagnosis and monitoring system of optical fiber link in substation. The whole system consists of distributed intelligent diagnosis center and online monitoring system, which has the functions of optical port power measurement, online monitoring and status diagnosis. When the system is applied in practice, it can greatly improve the measurement efficiency, avoid the damage caused by repeatedly inserting and inserting optical fiber during the debugging process and the interference caused by human factors, and promote the transformation of the stubborn disease of optical fiber link fault from " post processing " to " advance prevention ". It has the characteristics of flexible distribution and connection, which can directly carry out the operation equipment and shutdown equipment, and truly achieve the online monitoring and diagnosis of the whole life cycle. The developed system has been tested in the laboratory, and the corresponding functions have been verified.