A certain combine harvester cutting platform and grain allocation device was used to establish the geometric model based on Pro/E software and reasonably simplify by importing the model established into ADAMS. The virtual prototype model was obtained by adding constraints,loads and drives,and kinematics simulation was carried out on this basis. The range of the threshing device and other relevant parameters were obtained through the establishment of different drives and the simulation analyses of different working conditions of the threshing device. The results showed that only when the speed ratio was λ>1,the motion trajectory was cycloid,forming a closed buckle so that the spring teeth can push the crop stalk backwards. When the reel ratio of the reel is 1.55,it is closest to the best effect of the reel,which can meet the working requirements of normal work and avoid unnecessary falling loss. The maximum and minimum forward movement distances of the reel increase with the increase of pull-grain speed ratio. The forward movement range of the reel is 0.00-0.38 m.