In order to solve the problem that the voltage amplitude of the unsecured power signal cannot be accurately identified in the process of ESAD unsecured power signal, an optimization method for the unsecured power signal identification in ESAD is pro- posed. The method adopts the "digital + analog" recognition methods, using optical coupling isolation circuit as a way to identify digital quantity, AD sampling circuit as a way to identify analog quantity, "digital + analog" signal as the arming condition. By using analog recognition value as the threshold of initial judgment and digital signal to judge effectively, the reliability of ESAD function can be improved. The verification test shows that the identification method of "digital + analog" can effectively identify the signal and ensure the reliability of ESAD.