An array piezoelectric plate harvester excited by pneumatic compressed air was proposed to implement gas energy conversion and to satisfy the demand of energy supplying for low-power wireless sensors. By converting the alternate high air pressure energy in a pneumatic system into the electric energy with piezoelectric plates, the structure of a prototype for the array piezoelectric plate harvester system was designed. Then, based on the normal working states of the presented harvester, its working principles were introduced and corresponding experiments were performed. The theoretical analysis results show that the array piezoelectric plate has high output voltage capacities and collects the compressed gas energy effectively. An experimental prototype was fabricated by combing a piezoelectric single chip with a diameter of 12 mm and a thickness of 0.2 mm and an air cylinder with a diameter of 63 mm and a travel of 150 mm. A test system was built to research the performance of array piezoelectric plate harvester in simulated gas conditions. In the test, the pressures, cycles and flows were adjusted, respectively. Experimental results at the alternate high air excitation show that the proposed harvester collects the load gas energy of alternate high pressure air, and its optimal load resistance is 600 kΩ and instantaneous power is 1 052 μW, which meets the demands of low power sensors for energy applying.