Abstract: The elastic stability of thin plate has been paid much attention to with the increasing application of light and thin-walled structures. Elastic buckling of thin plates under various kinds of boundary conditions have been studied, such as plates on elastic support, plates with elastic rotation restraint and plates on rigid support with rotation restraint. The elastic buckling of rectangle plate on elastic support with rotation restraint along unloaded edges is not thoroughly studied yet and is complemented in this paper. A set of formulas for critical load is obtained by Ritz variation method, and the applicability of theoretic solution is verified through FEM (Finite Element Method) simulation. Factors affecting buckling modes as ratio, stiffness of rotation restraint and elastic support are formulated explicitly. Results show that the increase of support stiffness leads to the rise of both buckling half-wave number and buckling coefficient.