WPC making method that Sichuan birch was impregnated into compound solution mainly consisted of MMA and St/UPE then polymerized by using ,60,Co ,γ, rays is introduced. Some factors such as the porosity and the density of raw lumber, the condition of impregnation affected the impregnation of WPC were studied. The effects of the MMA St/UPE contents in impregnation solution, the absorbed dose and the polymer loating of WPC were also studied. WPC made by above optimum selection have excellent properties in comparison with its raw lumber: its abrasion resistence, impact indentation was respectively improved by three times,3.7 times. its water absorption and the swelling of wood was respectively reduced by 78.6 percent and 65.6 percent, and antishrink efficiencies was 65.7 percent.