Abstract: In order to explore the influence of different throat height on the hydraulic performance of winnowing inlet channel,establish inlet pools,inlet chamber and winnowing inlet channel inlet structure physical model and turbulence mathematical model,based on the Reynolds average N-S equation,the standard k-ε model is selected,SIMPLE algorithm is adopted,numerical simulation is carried out for the hydraulic performance of the dustpan inlet passage with the throat height of 0.7～0.9 times the impeller diameter,and the velocity distribution,hydraulic loss of the inlet passage,velocity distribution uniformity and velocity weighted average angle of the inlet passage with different throat height are analyzed. The results show that the flow velocity in the channel with high throat height is low and uneven after entering the winnowing chamber,the uniformity of flow velocity distribution at the outlet of the channel changes greatly with the flow,and the hydraulic loss of the channel is large. When the throat height is too low,the flow velocity is higher and the distribution is more uniform. The uniformity of flow velocity distribution has nothing to do with the flow size and the hydraulic loss of the flow passage is large. According to the analysis of the hydraulic performance of the channel at different throat heights,the optimal scheme is 0.8 times the impeller diameter. The hydraulic loss of the channel,the distribution uniformity of outlet velocity and the weighted average angle of velocity are 96.2% and 88° respectively,which are close to the ideal value of the objective function.