In the present study, the performance of a cylinder-based piezoelectric wind energy harvester attached to an elastic beam is numerically simulated. The wind flow perpendicular to beam axis causes an oscillatory aerodynamic force exerted on the beam tip. The beam and the piezoelectric layer are modeled as elastic continuous bodies, and the continuum governing equations of the solid and piezoelectric layers are extracted. Moreover, the induced lift force by the vortex shedding downstream of the cylinder is estimated by the modified van der Pol wake oscillator equation. The cantilever mode shapes and the Galerkin method is applied to solve the three transient and coupled equations of elastic deflection, electrical resistance and fluid force. Besides to verify the accuracy of the modified van der Pol equation, a moving object computational fluid dynamics (CFD) simulation is also conducted. The effect of oscillator length, cylinder diameter, resistance load, structure and piezoelectric thickness as well as the wind speed on the produced power is investigated. According to the obtained results, by increasing of the cylinder diameter from 0.05 m by 100, 200 and 300 %, the output power is increased by 219, 801 and 1502 % at the wind speed of 5 m/s.