A pultruded fiber reinforced polymer plastic (PFRP) structural member consisted of plate elements, which is commonly used as construction member, may be considered as an orthotropic material due to its unique manufacturing process. It has different mechanical properties with respect to the longitudinal and transverse directions. This orthotropic nature of PFRP material needs to be considered in the analysis of buckling behavior. In this paper, a simplified buckling analysis for PFRP plate using geometric mean of the longitudinal and transverse mechanical properties is performed. The comparison between exact buckling analysis and simplified buckling analysis is conducted. Each analysis is performed by the Levy method and the finite element method (FEM), respectively.