A newly designed extruder reactor for grafting vinyl monomers onto polyolefins was studied experimentally and theoretically. The process was made up of a self-wiping co-rotating twin screw extruder with a separated reaction zone and two vent zones. The reactive extrusion was performed using a linear low density polyethylene, vinyltrimethoxysilane and di-t-butylperoxide under different operation conditions. For the purpose of process analysis, we built a computer simulation based on the reaction kinetics and rheological models studied in the preceding paper. The flow field in the extruder was calculated by the flow analysis network [FAN) method with non-isothermal non-Newtonian flow conditions. The iterative procedure was organized to predict local pressure, filling factor, cumulative residence time and temperature along the extruder. Furthermore, we succeeded in representing the profiles of reaction conversion and shear viscosity. Calculated results showed good agreements with the experimental data.