The work aims to improve production quality of electrotyping free-standing diamond-nickel composite film, develop an improved response surface model and optimize multi-response parameters of electroforming process. Deposition process parameters of the electrotyping free-standing diamond - nickel composite film were regarded as object of study. On the basis of stepwise regression, regression model between factors and responses was built in response surface method. Its merits and demerits were explained, analyzed and inspected in the method of experimental design. Then, comprehensive regression model was obtained with response predict ability index as weight. Multi-response parameters optimization was converted to a single-response parameter optimization to make parameter optimization results preferentially optimize responses with strong predictive ability and improve overall optimization effects of process parameters. Finally, optimal parameter combination was searched in certain range in a constrained minimization function method with the comprehensive regression model as objective function, and the orientation of parameter improvement was given. The optimal parameter combination turned to be: diamond content of 16 g/L, cathode current density of 0.6 A/dm2 and deposition time of 1.5 h. The orientation of parameter improvement was given in the method of experiment design: additional experiment designs shall be performed in the area where diamond content was ＞16 g/L, cathode current density ＜0.6 A/dm2 and deposition time ＜1.5 h to get more optimal parameter combination. Quality tools, quality improvement method and statistical analysis method being applied to material preparation process can improve effectiveness of optimal process parameter selection, reduce the blindness of experiment design and achieve the possibility of a overall optimal parameters.