The springback of CNC bending reduces accuracy of tube bending, which leads to the wrinkle during subsequent hydro-forming, and to avoid the defect during hydro-forming, springback compensation is necessary. In this paper, theoretical model of tube plastic bending and strain hardening model of materials were set up firstly, and then the value of springback angle was derived. Meanwhile, several groups of experiments were carried out, and linear fit formula between springback angle and bending angle based on mathematical statistics was also obtained. Finally, the hydro-forming experiments show that the wrinkle can be avoided by springback compensation during CNC bending, and the dimensional accuracy of hydro-formed sub-frame is acceptable.