A tangential-longitudinal axial combined threshing and separating device was designed in order to reduce the loss of the rape when harvested. Kinematic analysis and high speed photograph were carried out on the course of the material flowed into the entrance of longitudinal roller, and the simulation analysis on the movement characteristics of rape cane moved in the longitudinal roller was done also by using the software ADAMS. The result showed that the materials could be flowed smoothly when the installing angle of longitudinal roller was 20° and the initial phase angle of telescopic tooth mechanism was 0°. The trajectory of rape cane moved in the longitudinal roller was a spiral along the inner wall of the roller shell. The impact between rape cane and teeth occurred in the radial plane.