By adopting the energy and finite-element methods with analysis software MATLAB and ANSYS

a detailed and complete solution process for bucking of simply supported rectangular elastic plates is provided.By increasing the triangular series for the deflection function

the amendments have been made to the K values given in references.Through finite element analysis

the expression of K value is fitted out.It is ascertained that the shear stress

taken as a critical shear stress

is reasonable according to the small deflection theory under limited plate deflection.The results of two analytical methods show that the fitting curve of K values used by finite element analysis has more comprehensive practical significance.