An optimization technique for process parameters of green sand casting of a cast iron differential housing cover based on the Taguchi parameter design approach is proposed in this paper. The process parameters considered are green strength, moisture content, pouring temperature, and mould hardness vertical and horizontal. An attempt has been made to obtain optimal level of the process parameters in order to yield the optimum quality characteristics of the cast iron differential housing cover castings. An orthogonal array, the signal-to-noise (S/N) ratio, and analysis of variance are used to analyze the effect of selected process parameters and their levels on the casting defects. The results indicate that the selected process parameters significantly affect the casting defects of grey cast iron differential housing cover castings. A confirmation run is used to verify the results, which indicated that this method is more efficient in determining the best casting parameters for differential housing cover.