In this paper, attempts were made to investigate the effect of resin and pigment concentration, pH of bath and also the processing factors of CED (Cathodic Electrodeposition) system such as constant applied voltage, the bath temperature and time of application on the final properties (such as thickness, appearance properties, physical & mechanical properties) of CED coated on the mild steel. The Taguchi L25 design was selected as the DOE model and the results were analyzed accordingly. The results showed that the constant applied voltage is the most decisive factor determining the final properties of CED coat. Pigment and resin concentration do not show a significant effects on the thickness but the optimum composition of these two factors determine the final properties of coated film. Apart from these three factors, pH and temperature have almost the same effect on thickness and final properties of coat. Coating time has the least effect on the final properties of the coat.