Aiming at the influence of side surface radius of curvature on the dispersion rules of fragment focusing warhead, the formation and dispersion process of prefabricated fragment focusing warhead with different curvature radius were simulated. Use the method of numerical simulation, the finite element model of the focusing warhead is constructed, and the process of forming the focusing band by the prefabricated fragments under different curvature radius is given. Through the fragmentation dispersion and velocity analysis of the fragments, the influence of the radius of curvature on the fragmentation velocity and the intensity is found. The simulation results show that the larger the radius of curvature of the side surface, the larger the fragmentation speed, the less the concentration. With the increase of the radius of curvature, the growth rate of fragmentation speed decreases. This calculation can provide a reference for the design of the prefabricated focusing warhead.