Abstract: The influence of processing conditions on the polypropylene melt flow in the flow channel of injection screw was analyzed in this paper. The three-dimensional nonisothermal flow fields of polypropylene melt in the flow channel of 35°cone non-return injection screw were simulated under different screw speeds and barrel wall temperatures using the finite element method. The fields of temperature, shear stress, viscosity and viscous heating of the melt were analyzed. Simulation results indicate that when the screw speed increases from 45 r/min to 105 r/min, the maximum velocity, the maximum shear stress, and maximum viscosity heating of the melt respectively increase by 1.60, 0.41 and 2.00 times, respectively, in the plasticizing process. When the barrel temperature decreased by 100K from 573K, the maximum shear stress, the maximum viscosity, and the maximum viscous heating increase by 1.13, 1.15 and 6.39 times, respectively, in the plasticizing process for a maximum velocity decrease of 0.011m/s. The corresponding increases in the maximum shear stress, maximum viscous heating, and the maximum viscosity of the melt are 1.32, 2.40 and 1.87 times, respectively, in the injection process for a maximum velocity decrease of 0.359m/s.