In view of the shortage of existing coaming formed, a telescopic support method was proposed,by which the work efficiency was greatly improved. Based on the theory of metal plastic forming, the springback law of plastic forming was deduced according to the plastic condition and the unloading principle of sheet metal in the course of sheet metal forming.Based on the principle of small deformation superposition of material mechanics,the deflection of bending roll was deduced.The minimum deflection dimension of bending roll was obtained by Workbench simulation design.The forming process parameters of the coaming were obtained through above calculation and simulation and the quality of the product was guaranteed.