Smart grid protection device plays an extremely important role in ensuring the safe and stable operation of smart grid in China. Protection device abnormal operation or fault behavior will affect the normal work of the whole electric power system, and even bring potential risks for the power grid. How to diagnose the abnormal operation and fault behavior of the protection device in time, and restore it to normal operation quickly, which is a major concern in power industry. The remote diagnosis system of relay protection device (RDSRPD) is developed based on the existing mature 4G mobile communication technology. It sets up a fast green data channel for the enterprise engineers to diagnose the abnormal problems of the protection device, which effectively solves the problem that the engineers must arrive at the scene to deal with the problem and processing time is too long, and wins valuable time for users. At the same time, the system provides the technical support for the joint diagnosis of the software and hardware development engineers of the protection device, which saves the cost of maintenance for the enterprise effectively.