A piezoelectric energy harvester with a right angle spiral cantilever structure which had a 2π radian was proposed. This design could reduce the resonant frequency on the one hand and improve the efficiency of energy collection per unit volume on the other hand. The thickness of the cantilever beam was 2 mm, the width was 6 mm, and the overall size was 22 mm×26 mm. When the acceleration of 0.1g excitation was applied, the simulated outpour voltage was 1.95 V, the output voltage measured was 1.8 V, and the relative voltage error was 7.7%. The simulated resonant frequency was 269 Hz, the measured resonant frequency was 265 Hz, and the relative frequency error was 1.5%. The theoretical output power was 7.04 μW, the measured output power was 5.79 μW, and the relative power error was 17.8%. This piezoelectric energy harvester had a wide application prospect in power supply of portable microelectronic devices.