The elevator brake is an important device to ensure the safety of the elevator, and is the basis to ensure the safe and smooth operation of the elevator. Its main function is to keep the car stationary when the elevator stops running, and to enable the running elevator to automatically stop the car in the case of power failure, its important position is like the brake device of the car, to ensure its reliable performance. The type test method is usually used to detect the performance of the elevator brake in our country. Due to the external influence of the equipment structure, the test parameters have one-sidedness and can not detect the performance of the elevator brake comprehensively and accurately. The traditional brake testing and testing is manual, and the choice of the distance, position and consumables of the brake lining mainly depends on the subjective experience of the operator, so it is difficult to achieve a unified standard in the maintenance and testing process. In order to solve the above technical problems, the symmetric difference algorithm of elevator brake action state detection is proposed to realize intelligent detection and improve the reliability and accuracy of detection.