In this paper, a piezoelectric piston gas compressor with a flexible drive is proposed to improve the gas driving capacity of a volumetric piezoelectric fluid driver. The operation characteristics of the gas compressor are theoretically and experimentally studied. A vibration model of the flexible support piezoelectric vibrator is developed. The effects of driving frequency and voltage on the vibration characteristics of the piezoelectric vibrator are analyzed through simulations. The flexible support piezoelectric vibrator is combined with a piston pump cavity to construct a piezoelectric piston gas compressor with a flexible drive. A flow-pressure calculation model of the gas compressor is developed to analyze the influences of cavity height and piston amplitude on the compressor output performance. The system resonance principles can improve the gas drive performance of the compressor. In addition, certain structural parameters of the system can optimize the compressor performance. Test results show that the gas output flow and pressure of the compressor are approximately linearly related to the driving voltage and significantly affected by the driving frequency. The best system output performance is obtained when the system operates in the resonance state. When the driving voltage of the piezoelectric vibrator is 220 V, the gas output flow rate and pressure of the compressor are 190 mL/min and 20.3 kPa, respectively.