The d15 mode PZT-51 piezoelectric energy harvesters(PEHs), which of piezoelectric layer thicknesses were 0.6 mm,0.7 mm,0.8 mm,and 0.9 mm respectively,were designed and fabricated. The curves of vibration frequency versus output voltage and output power were measured at open circuit and load resistance of 1 MΩ,and the dependence of output peakpeak voltage on input vibration excitation voltage was also tested at load resistance of 1 MΩ.It is shown that with the decrease of piezoelectric layer thickness,the resonant frequency of PEH decreases, while the output voltage and output power increase. The laminated structure d15 mode PZT51 PEH with piezoelectric layer thickness of 0.6 mm shows the maximum open circuit output peak voltage of 1.69 V and maximum output power of 0.708 μW at load resistance of 1 MΩ.