Abstract: With the elastic-plastic theory, the characte ristics in all stages during the forming process of the double metal clad pipe are analyzed and the calculation formulas of the maximum and minimum hydraulic expansion forming forces are determined. Through the finite element numerical simulation analysis, the correctness of the theoretic calculation is verified and the local corrugation of the inner lining pipe, occurred when hydraulic expansion forming force is too large, is also analyzed by simulation. Both the theoretic analysis and simulation result can lay a good foundation for the industrialized application of the hydraulic expansion forming of the double metal clad pipe.