The numerical simulation of the filling process of complex magnesium alloy casting was performed with Any Casting software. The air entrapment of magnesium alloy casting during filling process was studied. And flow behavior of liquid metal was analyzed in the process of die casting. According to the analysis results, optimization scheme was proposed,that is the fan gating system becomes many crossings system. And flow path of liquid metal at gate is changed. Thus, the filling of liquid metal in the cavity i...