Abstract: To explore key factors affecting throwing efficiency of silage machine throwing arm system, anemometer was used to measure wind speed inside throwing arm, and a high-speed camera was used to capture velocity of material particles at different positions in throwing arm to obtain initial test data．CFD-EDEM coupling was used to simulate physical motion process of material thrown by throwing arm system, and simulation results were compared with test data to calibrate simulation input parameters．On this basis, multi-physical field structure optimization of throwing arm structure was completed by HyperStudy, and average velocity of particles at outlet of throwing arm and differential pressure between inlet and outlet of throwing arm were analyzed under different throwing arm structures, to obtain a better throwing arm structure．Simulation verification showed that average output speed of particles at optimized throwing arm outlet increased by 15.93%．Compared with test results of original model, optimized prototype increased material particle throwing distance by 175%．Throwing arm structure wear reduced, and material particle motion consistency has been greatly improved, to meet design requirements of high speed and small scattering range of silage machine throwing arm outlet．A feasible technical route was provided for multi-physical field coupling optimization analysis of silage machine throwing arm system throwing efficiency．