Functionally graded materials (FGMs) have been widely used in many structural applications over the past decades. The rapid growth of the FGMs is due to their remarkable mechanical and thermal properties. The mechanical buckling analysis of functionally graded ceramic-metal rectangular Plates is considered in this paper. The two-variable refined Plate theory (RPT), in conjunction with the bubble finite strip method, is employed for the first time to evaluate the mechanical buckling loads of rectangular FGM Plates. The theory, which has a strong similarity with the classical Plate theory (CPT) in many aspects, accounts for a quadratic variation of transverse shear strains across the thickness of the Plate and satisfies the zero traction boundary conditions on the top and bottom surfaces of the Plate without using the shear correction factor. In comparison with the ordinary finite strip method, the convergence of the bubble finite strip method is very rapid due to using bubble shape functions. The mechanical properties of the FGM Plate are assumed to vary according to a power law distribution of the volume fraction of constituents. The accuracy and efficiency of the present method are confirmed by comparing the present results with those available in the literature. Furthermore, the effects of power-law index, Plate thickness, aspect ratio, loading types and various boundary conditions on the critical buckling load of the functionally graded rectangular Plates are investigated.