For the shortcoming of the firing pin in the firing mechanism, the collision of certain cannon fire mechanism is analyzed and calculated in this paper from the angle of the collision mechanics. The collision and impact force of the firing pin are analyzed. The finite element model of the cannon firing mechanism is built with the ABAQUS (the finite element analysis software), and then its finite element simulation is calculated. The calculated data include some parameters, such as stress, velocity and displacement of the hammer and the firing pin. According to the analysis of the simulation, the paper concludes that during the components’ collision the slender rod is more prone to fatigue fracture. Then, focuses on the analysis of the dangerous section of the firing pin and put forwards some improving measures, which are of great significance to prolonging the serving life of the firing pin.