In this article, the buckling behavior and bifurcation point of Functionally Graded Piezoelec- tric (FGP) beams are investigated based on Euler-Bernoulli beam theory. The finite element method is employed to model the beam in thermal environment. The material properties of the beam are considered to vary gradually in the thickness direction and the beam is subjected to electrical and thermal loading. In this paper, direct and inverse piezoelectric effects are considered and buckling of the beam in the sensor state is investigated. By solving the eigenvalue problem, the buckling load of the FGP beam is obtained and the effect of various parameters such as power law index, temperature, applied voltage and beam aspect ratio on the buckling load are investigated. The results show that the boundary conditions are the main factor that affects the buckling load of the FGP beam.