Abstract: According to the three-dimensional elastic equilibrium equations and the conditions of interfacial shear slip, a model of interfacial shear slip of laminated composite plates is developed. The shear slip is described by the linear interfacial constitutive relations of transverse shear stresses and in-plane displacement jumps on weakly bonded interfaces. The model takes the same form of displacement field and equilibrium equations as the general two-dimentional plate and shell theories do, but it is relatively simple and very accurate because the shear deformation functions, which account for bonding conditions on the interfaces and the traction boundary conditions on the lateral planes, are introduced. The closed-form solution of simply supported cross-ply plates is obtained. Bending and buckling of laminated plates are considered and the effects of interfacial weakly bonding are discussed. The numerical results are compared with the exact solutions and show the high accuracy of the present model.