Abstract: Three dimensional finite element numerical simulation coupled with scalar mixing analysis was employed to investigate the effects of feeding condition,rotating speed and feed monomer ratio on reactive extrusion of polyurethane.The reaction course is controlled by the residence time and the degree of homogenization.The polymerization degree with non-premixed feeding is lower than that of permixed feeding.Higher rotating speed is beneficial to homogenization,while it also leads to the reduction of residence time.Therefore,the rotating speed should be optimized according to the mixing-reaction characteristics.Results show that higher polymerization degree in current study is obtained under 90 r/min.Moreover,the effect of prepolymer feeding on reactive extrusion is also simulated.Results indicate that the polymerization degree can be controlled via two-step feeding in order to improve the stability of reactive extrusion and to match the appropriate reactors for various reaction periods.