The invention discloses a thyristor protective trigger detection method. A time interval between the last forward voltage indicating pulse IP before a control pulse CP and the CP is determined, if the time interval is more than certain time, a thyristor protective trigger detection window is generated at a trigger pulse FP falling edge, if a thyristor return signal is received in the window, thyristor protective trigger is determined; otherwise, a thyristor protective trigger detection window is not generated, and the received thyristor return signal is determined as a forward voltage indicating pulse. The thyristor protective trigger protection maloperation problem under conditions that the trigger angle is too small and the IP dispersion is too large and occurred frequently during practical engineering is solved effectively. After examination and comparison of practical engineering, the method is proved effective.