Piezoelectric materials have long been used as sensors and actuators; however their use as electrical generators is less established. Such materials are capable of converting mechanical vibration energy into electrical energy, but developing piezoelectric generators is challenging because of their poor source characteristics (high voltage, low current, high impedance) and relatively low power output. This paper presents a theoretical analysis and design of piezoelectric power generation in low frequency applications (2 to 5 Hz), where the design method is obtained by a piezoelectric equivalent circuit and an analysis of internal stress. Some important considerations in designing such generators are explored, including of parameter estimation, load matching, efficiency, energy conversion, and energy storage. A prototype hand-shaking piezoelectric generator is proposed, which can be used to drive a wireless-switch device (the driving voltage being 5V). Experimental results show that the average electrical power in the hand-shaking piezoelectric generator can be approximated to 48.5 mu W.