In order to satisfy the technical requirements of the primary circuit of submarine nuclear power, aimed at the disadvantages of the original shuttletype check valve having large pressure gradient increasing, frequent vibration of the shuttletype check valve, unstable operation of the valve, larger water hammer and flow resistance caused by its volume mutation of A and B two parts, its valve body was optimally designed through numercial simulation analysis by using FLUENT software. Its macroscopic velocity, static pressure and flow resistance coefficient were analyzed with comparing before and after optimization. The results show that the flow lines curvature of the optimized shuttletype check valve is increased, and lines transition is more smooth and continuous. The overall flow process is stable in velocity, followed with increasing of flow capacity of the valve and decreasing of vortex strength, uniformly forcing of the valve core, and decreasing of water hammer on the valve core and flow resistance. Its relatively lowering amount of flow resistance coefficient is more than 60% in the opening of the valve between 5% and 20%. Consequently, the antiwater hammer characteristics of the valve are obviously improved.