The gating system of a cylindrical magnesium casting has been designed by using multiple objective optimiza- tion and Taguchi method.Mold filling and solidification processes were simulated by using MAGMASOFT(?). The simulation results indicate that the gating system design has a significant effect on the quality of magne- sium castings.In an effort to obtain the optimal design of gating system,the signal-to-noise (S/N) ratio was used to analyze the effect of various gating designs on cavity filling and casting quality by using a weighting method based on the design of an orthogonal array.Four gating system parameters,namely,ingate height, ingate width,runner height,runner width,were optimized with a consideration of multiple objective criteria including filling velocity,shrinkage porosity and product yield.