In this paper, the variation transmission model is introduced to build the key quality characteristics identifying model in multistage manufacturing process. Then the PLSR (Partial Least Squares Regression) method is used to solve the multicollinearity problem of the quality characteristics, make model analyzing and identify the key quality characteristics. At last, the aircraft parts manufacturing process is taken as an example to present the application of this method. The result shows that this method can show the variation transmission relationship of each quality characteristics in every stages and its impaction on the final product quality, and then identify the key quality characteristics, provide the direction for implementing quality control and improvement..