The piezoelectric material has the ability of transfer vibration kinetic energy into electric, but the generated power is weak with AC characteristic. It is necessary to establish storage circuit to accumulate the generated power and supply steady DC current. Based on the piezoelectric constitute equation, the coupling modeling of piezoelectric energy harvesting system is established. The numerical simulation is performed for the output voltage and power. A storage circuit with capacitance is designed and fabricated, which provides steady DC current with voltage comparator and regulator. The performance of the circuit is verified by experiments and the efficiency and the error are discussed and analyzed. The results show that the storage circuit can provide 2.24 V steady DC current, the storage efficiency is up to 66.3%.