The piezoelectric vibration-based power generator is a promising MEMS electricity source to power wireless sensing nodes for the fault diagnosis of rotary machines. In this paper,a piezoelectric vibration-based power generator is designed and the mathematical model of the cantilever piezoelectric generator used in rotary mechines is established.Then,the effects of the axial extension force on the stiffness of the beam and the frequency of the generator are analyzed,and the formulas of the frequency, output voltage and output power of the cantilever piezoelectric generator are derived. The output property of the piezoelectric vibration-based generator fixed on a rotary frame is measured.Obtained results show that the maximum output power of the generator is about 35 μW at the rotation frequency about 14.25 Hz. The output power decreases quickly when the rotation frequency deviates from the frequency of the generator.