The energy harvesting efficiency is a key issue for the application of the micro ring tone oscillations piezoelectric generator on fuze．The traditional energy harvesting circuit and valley fill energy harvesting circuit was described，on which a higher energy harvesting efficiency synchronous charge energy harvesting（SCEH）circuit was designed based on PWM technique and SCEH methods. Electric energy transferring time was precisely controlled by the micro switch．Theoretic analysis and experimental simulation revealed that the micro switch could precisely controlled SCEH circuit, and the output power was maximum with nothing to do with variable load resistors，which would be helpful for application of micro ring tone oscillations of piezoelectric generator on various fuzes．