Abstract: To improve the operation stability and construction economy of the seawater circulating pump in nuclear power plant, the elbow inlet channel of the seawater circulating pump was optimized based on CFD numerical simulation. Taken the inlet flow path of a domestic nuclear power plant as the research object, a new coordinate system was established. The functional relationship among parameters of the elbow flow path control was obtained by theoretical deduction. According to performance evaluation indexes of the flow channel, the influence of the four main parameters of the elbow inlet channel on its hydraulic performance has been studied by numerical simulation. Meanwhile, the optimized elbow inlet channel was verified by experiment. The results show that under the design flow rate, the average flow velocity at the outlet of the optimized flow channel is increased by 0.026 m/s, and the uniformity of flow velocity distribution is reduced by 0.13%, and the average flow angle is increased by 0.034°, and the hydraulic loss decreases by 11.2%. It can be seen that the elbow channel optimization design method proposed in this paper is fast and reliable, and has the advantages of good outlet flow pattern and small hydraulic loss. It can provide a favorable reference value for the establishment of the project.