With the rapid development of sensor network in Internet of Things, the weak energy harvesting circuit has attracted much attention due to lots of advantages. In this paper, a circuit based on piezoelectric energy harvesting technology is designed, which collects the lowfrequency mechanical vibration energy in the environment, generates AC voltage through PZT piezoelectric ceramic transducer, and then amplifies it through quadruple voltage circuit, and rectifies and transforms through the LTC35881 power management circuit, eventually generates a switchable standard voltage for lowpower sensor operation. The experimental results show that the circuit can effectively support the low power sensor to operate normally.