The mathematic model for polymer extrusion has been established by using the penalty finite element method, and the analysis program has been coded. The driven and pressure flow of power-law fluid in compound shaped part of co-extrusion process of polymer with metal insert has been simulated. The velocity field and temperature field of polymer flow in die cavity are obtained though solving the momentum equation and energy equation, and the influence of various metal insert velocity on the polymer flow is studied. The potential defect is forecast, and the improved measure has been given further. It shows that the common rule of the compound shaped part of co-extrusion process of polymer with metal insert is given by the analysis of the example. The simulation results are very important for the process and die design of the polymer co-extrusion with metal insert.