Abstract: An improved model of lamination theory was used to forecast the mechanical properties of ionic polymer metal composite (IPMC). The outer layer doped with saturated metallic atoms was used as the exterior plating layer，the pure polymer was used as the middle layer，and the material between the two layers，in which the metal content gradually varied，was a gradient layer. Because of Pt content in thickness of Pt-IPMC was detected using EDS method，the rationality of the model was proved. The tensile and bending modulus were tested by the ASTM standards. The elasticity properties of the outer and the gradient layers were predicted by Mori-Tanaka method，and the properties of IPMC were obtained by using gradient mechanics. The tensile performance of IPMC under normal and saturation conditions was estimated and compared with the experiment results，the error of tensile module under normal and swelling conditions is 0.69% and -2.05% respectively，while the error of apparent bending module under normal conditions is -0.99%.