The application of lightweight materials is one of the main measures to reduce weight in mixed-flow pump.A mixed-flow pump was developed based on CFturbo software,and the scheme of using different combinations of lightweight materials in the impeller and guide vane was proposed.Based on CFD simulation of unidirectional fluid-structure coupling technology,six alternative schemes were evaluated comprehensively from the aspects of external characteristic curve performance,stress and deformation of impeller and guide vane,the feasibility of unidirectional fluid-solid coupling technology analysis methods for mixed-flow pumps using lightweight materials was verified.The results show that:the impellers with different materials have little influence on the performance of the mixed flow pump;under different flow rates,the maximum stress and deformation of the impeller and guide vane with different materials occur at the blade rim and guide vane inlet respectively,and the maximum stress and the maximum deformation decrease with the increase of flow rate;in the three feasible combination schemes of impeller and guide vane with light materials,the total mass of the mixed flow pump is at least 29.74 kg,and the weight loss ratio is 16.86%.The maximum weight is 32.08 kg with a weight loss ratio of 10.32%.