Aiming at the problem that it is difficult to calculate the fatigue life of the key components of CT601-8 operating mechanism affected by the impact loading at high crash rate, a modified local stress-strain method is proposed. In order to solve the problem that the stress-time curve of roller pin shaft can not be measured in the impact process, the static simulation of the whole model is carried out. Then combined with the display dynamic LS-DYNA numerical calculation, the stress dynamic changes of key parts are obtained. Last by comparing the measured data with the simulation results and according to the modified Manson-Coffin formula, the model for calculating the impact-fatigue life is obtained. The results show that the stress concentration part of roller and door lock slab is the same as the failure zone of parts in the actual test process, and the equivalent stress of door lock slab is similar to the simulation results with the relative error of 18.27%. The fatigue life obtained by the modified local stress-strain method is 1862 times, 12.3% different from the actual life. The simulation results have important reference value for the calculation of the fatigue life of this type of spring operating mechanism.      Key words: