The utility model provides an auxiliary frame, which comprises an auxiliary frame body, a vehicle body connecting part is constructed on the auxiliary frame body, the upper surface of the vehicle bodyconnecting part forms a vehicle body mounting surface, and corrugated structures with the same height are constructed on the vehicle body mounting surface. According to the auxiliary frame disclosedby the utility model, the equal-height corrugated structure is arranged on the vehicle body mounting surface connected with the vehicle body; when the auxiliary frame and the vehicle body are assembled, a deformation space can be formed in the vehicle body mounting surface, so that plane errors caused by manufacturing are reduced, auxiliary frame deformation caused by planeness when the auxiliaryframe and the vehicle body are assembled is reduced, meanwhile, internal stress generated by assembling is reduced, the assembling precision can be improved, and the NVH of the auxiliary frame is further improved.