In this paper, the optimization of cutting parameters in turning thin-walled 45Cr steel workpieces with cermets tool is researched. A new integrated optimization method is proposed, in which the parameter design of the Taguchi method, principal component analysis method and response surface method (RSM) are applied to obtain the optimal parameter for a hard turning process using mixed cermets tools. The orthogonal array experiment is conducted to economically obtain the response measurements. The Principal Component Analysis (PCA) is applied to transform the original evaluation variables into new, uncorrelated comprehensive variables, which includes most information of original variables, then the output response can be calculated by the principal components. At last, the RSM is used to build the relationship between the input parameters and output responses, and obtain the desired machining parameters. The quality of workpieces and the process efficiency are improved obviously.