Abstract: The change of binder volume fraction was simulated by CFX software based on the two-fluid model during poweler injection molding(PIM) filling flow.The results show that the binder content of the thin surface layer is more than the mean of the whole injected parts.The volume fraction of the binder decreas gradually from surface to interior.So,the PIM unique boundary layer effect is verified.The effect would be amplified gradually as the temperature of injection increased from 420 K to 440 K,but it is lightened as the flow rate increased from 60 cm3·s-1 to 80 cm3·s-1.It is fitted with the practice results basically,so the two-fluid model is reliable to study the PIM filling flow.