A new type of stainless steel(Outer thin wall)-concrete-steel double walled hollow tube is presented in this paper. By using the basic assumption of the composite structural elements and the constitutive relation of the materials, this paper analyzed the bending bearing capacity of the normal section. Using the cross section method, the calculation formula of the bearing capacity of the bending members(DSTM)is established. Beside that, the finite element numerical method is used to analyze the results of the cross section method. The study show that the results of the two methods are basically consistent, and the formula can provide reference for engineering design.