In order to understand the influence of feeding height on the distribution of gas phase flow field in a cyclone separator and improve the cleaning efficiency of the wind cleaning device. A cyclone separator in 5TY–100 type rape thresher developed by Hunan Agricultural University was modeling by using gambit for 3 kinds of feeding height (50, 150 and 250 mm). The model was imported into the fluent to simulation. The simulation results showed that the feeding height does not affect the axial size of the vortex core in the cyclone separator, which had an effect on the negative pressure, airflow velocity, tangential velocity and vortex core volume. As a decrease in the feeding height, the negative pressure in the cyclone separator decreased, and the gas flow velocity, tangential velocity and vortex core increased. It is found that a high material cleaning efficiency could be achieved on the lower feeding height.