There are many kinds of casting defects such as insufficient pouring, cooling separation, crack, and shrinkage and soon on were formed in the mold filling and the solidification process, which affect the final casting performance. Based on the mathematical models of mold filling and solidification process, the numerical simulation of chilled cast iron camshaft in sand casting process has been done. The filling behaviors at each stage in the filling process were presented. The temperature distributions in the solidification process were obtained, and the positions of shrinkages were predicted. According to the simulation results, an improved technology is proposed, and the shrinkages were eliminated efficiently. The simulation results are in good agreement with practical.