In view of the detection of safety protection device for escalator/automatic sidewalk comb plate，a highprecision，portable and simple detecting device is developed based on highspeed microcontroller STM32. The device was included of trigger module，displacement detection module，embedded micro control system module and computer management module, and etc. The inclusion of foreign matter could be simulated between the comb plate and the pedal surface，causing vertical displacement or horizontal displacement of the comb plate，stopping the escalator/automatic sidewalk in time by triggering the safety switch of the comb plate. Thus，the reliability of the safety protecting device of the comb plate could be tested，and the force size and movement displacement of the comb plate could be detected，so as to quantitatively evaluate the flexibility of the safety protecting device of the comb plate. The prototype test results show that the trigger module of the device is reliable in operation，accurate in measuring force，small in measuring displacement error，fast in installation and easy to operate. It is suitable for the use of elevator manufacturer，elevator installation maintenance unit，special equipment inspection institute and elevator quality supervision and inspection organization, and etc.