. For the purpose of improving the output power of piezoelectricity generator (PG), this paper derivates the improving equivalent circuit of piezoelectricity element according to piezoelectricity effect. The dielectric loss and conductive loss are considered. The dielectric loss is caused by the hysteretic effect between leakage current and electric intensity in the medium inside. The conductive loss is caused by the ceramic particles boundary conditions. The relationship between output voltage and current is set up. The relationship between resistance and output power is set up. The relationship between output voltage and out power is set up. Those relationships are simulated and experimented. From the results, it is can be known that there is an optimum load(200 ) for the maximum output power (70 ) in condition of fixed structure, size and fixed excitation frequency and amplitude. With the increasing of voltage, the current is decreasing with parabolic form and the output power increases lowly to a maximum power firstly, and then decreases fast.