This paper proposes a piezoelectric energy harvester based on a trapezoidal piezoelectric cantilever using the d33 mode of the piezoelectric materials. The trapezoidal cantilever structure can improve the average stress of energy harvester and reduce its maximum stress, thus it can increase the output voltage and service life of the harvester. In another word, the d33 coefficient of piezoelectric materials is 2 3 times of the d31 coefficient, thus the use of the d33 mode of piezoelectric material can increase the output voltage of the energy harvester. The energy harvesters of d31 mode and d33 mode with the same size are analyzed, manufactured and tested. The experimental result shows that the output voltage of d33 mode is about 2 times of the d31 mode with a higher output voltage and is identical with the result using finite element analysis.