Abstract: Taking the structure system as a sandwich compositeelement, a calculation model is proposed, and the lateral displacement of thestructure, shearing force and bending moment of the componentsare obtained according to deformation compatibility. Thecalculation analysis shows that shear force distribution of components isonly related to with stiffness and width of components, and shear stressin upper internal composite slab is larger than that of lower slab;bending momentdistribution coefficient of components decreases as \lambda increases, and whole structure is strengthened, and when \lambda is enoughlarge, mechanical behavior of structure is similar to a cantilever member.