Abstract: CFD software is applied to analyze the hydraulic characteristics on the main check valve flow model about multi-loop reactor. The outlet non-uniform flow of reactor coolant pump is used to calculate the hydraulic moment of the valve under the full-open condition. By analyzing the key structure factors and its effect on the hydraulic characteristics, the valve configuration was optimized. The results from the improved model show that the pressure drop through flow near the inlet and outlet region has been reduced, and the position of disc has been kept the whole opening,which could avoid the effect of pump-valve coupling operation.