In the present research, a new modeling approach for elastic composite plates is studied. By adopting mixed variational formulation and dimension reduction method along the thickness, a general plate model is derived. Firstly, shape functions weighted with arbitrary coefficients adopted along the thickness of plate for both displacement and stress field and then, partial differential equation system of plate is derived by using the Hellinger-Reissner principle. Moreover, a comparison between current work and other theories such as Classical and First Order Shear Deformation Theory has been done, and advantages of this method are discussed Needless of shear correction factor, more accurate results and independent stress from displacement filed are some advantages of this approach.