Fine micro structure and high mechanical properties are requested in vehicle using sheet. But the quality of sheet is very difficult to control given many influencing factors in the manufacturing process. In this article, a microstructure control system applied to vehicle using sheet was established with the theory of Ultrafine Grain and Artificial Intelligence. The method of optimal discrimination plane (ODP) was employed to analyse the key factors and weigh of the parameters influencing the microstructure and mechanical properties of the sheet, such as component and deformation process parameters. According to the analysis, the partial least-squares (PLS) method is applied to set up the mapping relationship between influencing parameters and microstructure, performance. Then an optimized process scheme is obtained. The results showed that the key factors influencing the microstructure and mechanical properties were respectively the temperature and deformation amount of the first pass and the first interval. An optimized process scheme was below: t₁800; eI25%, τ₁4, and the finest microstructure and highest mechanical properties of the sheet were obtained: F_fine%=87%.