In the sheet metal CNC incremental forming process, model posture determines the forming half cone angle, which has a great effect on the forming sheet thickness thinning rate and distribution. In order to form the sheet metal part according to the optimal direction of the sheet thickness uniformity and avoidto form along the direction of the sheet thickness thinning rateoverlarge in some local area. The CAD model to be formed should be repositioned and redirected according to the desirable pressing direction through model transformation. In this paper, threedimensional transformation algorithm and location algorithm for the CAD model to be formed have been presented, which made the sheet forming possible according to the desired directions of users.