The safety helmet on the two side plate between the brim outside and as close as possible to the pressure plate, the test machine safety cap through the plate, 30N is applied in the vertical direction of the plate, keep the 30s record for the Y1 tablet at this time interval, and then loaded with a speed of 100N/min until 430N, 30s, and record the distance the plate is Y2, at a rate of 100N/min load to 25N, then immediately at the speed of 100N/min will increase the load to 30N, and maintain 30s records at this time for the Y3 plate spacing, the measurement should be accurate to 1mm, and record the possible failure phenomenon, Y2 and Y1 for calculating the difference between the maximum deformation. The difference between Y3 and Y1 for the calculation of residual deformation.