Abstract: A bimodulous rectangular plate could form an isotropic compression and a tensile area under external loads. Thusly, a bimodulous rectangular plate was regarded as a laminated plate composited of two kind of isotropic material. The static equilibrium equation of the bimodulous rectangular plate under the condition of external loads was established by using elastic mechanics theory. The location of the neutral plane in the bimodulous rectangular plate was determined by the utilization of static equilibrium equations. The large deflection bending deformation differential equations of the bimodulous rectangular plate was derived, and the middle point deflection of the bimodulous rectangular plate was gained with method of weighted residuals. Then the calculation results were compared with that obtained by finite element method, and it show that the method above is reliable. Meanwhile the effect of the bimodulous on the large deflection bending deformation of a rectangular plate was discussed and analyzed.