At present, the research on the judgment of the correctness of relay protection function in intelligent substation focuses on the overall evaluation of protection system or the judgment of the correctness of protection execution process, and lacks the real-time evaluation of the status of various types of protection functions and the logical judgment of the trigger of protection functions.The status of each protection function are classified and evaluated by analyzing the influencing factors and influencing logic of each type of protection function.The correctness of protection function trigger is judged by capturing and analyzing the sampling value with the state of devices.The information sequence generated by the secondary system when the protection function is triggered is sorted out, and the correctness of the protection function execution process is judged by comparing the theoretical sequence with the actual sequence.At the same time, the pre-condition is added to solve the problem of selecting and matching different information sequences when the same protection function triggers.Through the analysis of field examples, it is verified that the method proposed in this paper can provide a theoretical basis for the monitoring of protection status and fault analysis of smart substation.