Based on cold rolled TRIP 780 and HSLA 340 steel sheet, the stamping of U-beam and its springback was studied experimentally and numerically. Collision analysis model of closed hat section beam was established on the basis of simulation analysis of U-beam stamping and springback. Mapping was used to transfer results of thickness, stress and strain from U-beam forming part to impact structural part. Collision processes of closed hat section were analyzed under various operating conditions considering the influence of forming. The results show that thickness variation, residual stress, and work hardening of the material after forming affect collision processes directly. The current paper provides reference for improving precision of simulation for vehicle collision.