In this paper, a higher-order plate element has been developed to analyze the critical buckling loads of the bimodulus laminates. The bimodular material exhibits load- dependent elastic properties, i. e. the tensile Young's modulus is different from the compressive modulus. It makes the behaviour of bimodulus laminates a nonlinear problem. Therefore, the neutral plane of the plate is not fixed in the midplane surface. The neutral surface is then determined by the iterative method herein. An uniform in-plane stresses are assumed distributed through the thickness in the buckling analysis. Through the purtabation technique, the governing finite element equations for the stability analysis becomes a generalized eigenvalue problem. To demonstrate the accuracy and efficiency of the present study, several benchmark problems are illustrated. Simple-supported square laminates of different span-to-width ratios and modulus ratios are investigated. The locations of neutral surfaces and the critical buckling loads are evaluated. Compared to the analytical solutions, excellent results and fast convergence are observed.