In this paper, the shape influence of piezoelectric beams including triangle, trapezoid, rectangle, inverted trapezoid, convex parabola, concave parabola, and comb-shaped (a combination of two triangular beams with a connector of 4 mm length) are addressed and analyzed by FEM. The analysis is performed for a bimorph piezoelectric beam. The analyzed parameters include the beam length, thickness and width of the piezoelectric layer. The study is performed using COMSOL Multiphysics software for all seven shapes. The results show that due to the mechanical properties of the beams, the natural frequency of the triangular beam is more for all considered parameters. In addition, as the width of the beam end increases, the natural frequency reduces, too. Since natural frequency is inversely related to electric power, the inverted trapezoidal beam has the highest electric power and the triangular beam has the lowest one.