The signal quality of auxiliary system is very important for substation to assure operation in safe conditions, but the external environment like electromagnetic interference, high or low temperature, and equipment aging will directly influence the video signal quality tran sferred by the auxiliary system, which makes a high demand for the cracking resistance of the auxiliary system device. This paper designs a signal quality simulator for substation auxiliary system and simulates common damage situations in the substation to reproduce the real damage situations in the laboratory environment. The results show that this simulator can provide a tesearch platform to test the capability of anti-interference and data recovery of the auxiliary system and so on.