On the basis of the mathematical elastic theory, the bending deflection expression of the complex Fourier Series is derived at first for the infinite plate with a unit circle.

In this paper a new analytic solution to large deflection of stiffened plates is presented.

In this paper, the modified method of multiple scales is applied to study the bending problems for circular thin plate with large deflection under the hinged and simply supported edge conditions.

Based on minor deflection bending theory of elastic thin-slab,this paper puts forward the calculation method of quadrilateral simply supported slab under the arbitrary vertical loads;and by means of the revision of boundary condition this calculation method can be adopted in designing slabs with all sort of support.