The AC-DC transferring circuit greatly affects the output performances of the piezoelectric vibration generator (PVG). In order to improve the output performance and the energy conversion efficiency of the PVG,this paper presents the equivalent circuit model of the PVG at first,and then the analytical expressions of the ACDC circuit, such as the output voltage and the output power,are derived by using the mechanical equilibrium principle and circuit theory when the PVG operates under the steadystate.To maximize the output power of the ACDC transferring circuit,the optimization of the output power with different resistance loads are carried out by using differential calculation method,and the optimal load resistance,displacement, output voltage and output power are obtained 〖HJ〗under the opencircuit resonance and shortcircuits resonance condition respectively.Some simulations are carried out to analyze the output performances of the PVG.The validity are performed by compared the results with the coupling analysis results of Ottman and the inphase analysis results of Guyomar. The results have shown that the optimization of the output performance of the ACDC circuit is attributing to enhance the total performance and the energy conversion efficiency of the PVG.