In view of the technical problems of large fluctuation, poor stability and large meshing impact force in the process of roller chain transmission, the meshing force in the process of transmission can be reduced to improve the tooth profile by analyzing the consistency of sprocket tooth profile angle. The simulation model of roller chain and chain sprocket was established by Abaqus software, and the curves of fluctuation, meshing impact force and velocity inequality coefficient, and the nephograms of space velocity, space displacement and stress component of the chain were obtained by simulation. The credible comparison standard fluctuation △h and velocity inequality coefficient k were used to evaluate, and the shooting test was carried out. The results show that the design scheme of roller chain transmission mechanism of chain machine gun with epicycloid equidistant gear is effective and feasible, which can improve the dynamic performance of chain machine gun in reliable transmission.