To solve the forming defects of the inside wall of small-radius tube wrinkling and the outside thinning, a bending-bulging compound forming has been put forward. The range of the initial bending radius is determined by analyzing the geometrical relationship among the initial bending radius, the initial tube diameter, the final pipe diameter and the final bending radius. The influence of different initial bending radius on the wall thickness distribution and bulging on the straight and deformation wall are studied by FEM simulations and experiments. Finally, the results show that the larger initial bending radius is, the smaller thinning of the parts is. At the same time, the uniform thinning appears at bend, and thinning at the inside of the straight wall is obviously larger than that at the outside during the bulging process.