In order to explore the distribution law of flow path in isothermal twin screw extruder under isothermal and non isothermal state,using Solidworks 3D modeling software to establish the physical model of meshing counter rotating twin screw extrude, the corresponding numerical simulation is carried out in the Polyflow analysis software.Numerical results show that: in the isothermal problem, the pressure, viscosity and shear rate of the exit direction vary with the increase of the speed of the twin screw; in the non isothermal problem, with the increase of the rotating speed of the twin-screw, the direction of the extrusion direction increases from the inlet to the outlet, and the temperature increases gradually along the radial direction. It can provide theoretical basis for further optimization of process parameters.