In this paper, 3-D geometry of the camshaft castings was constructed via CAD software Pro/ENGINEER, and the filling and solidification simulation of the castings was carried through the ProCAST computer simulation code. The results showed that: while the castings solidifying, the runner and the riser solidified firstly, forming restraint at the ends of the camshaft and confining the solidification shrinkage along the axis. There were two main hot spots in the castings when solidifying, one at the underside of the camshaft, another at the upside. In the hot spots at the underside near the runner, the feeding condition was better because the liquid pressure was higher, and the solidification rate was slower, producing less stress. While in the hot spots at the upside close to the riser, the feeding condition was worse because the riser solidified firstly and the solidification rate was quick, producing higher stress and hot tears. In addition, the effects of pouring temperature and riser size were also discussed. Based on above, the initial gating and risering system was modified and tested in production, and satisfactory results were achieved.