Triboelectric nanogenerator (TENG) exhibits considerable application prospects in many fields, which highlights the importance of the structure of TENGs. Various types of TENGs have been proposed and developed, nevertheless, the TENGs still face defects in structural stability, flexibility and environmental adaptability. In this work, we reported a novel air supported-TENG (A-TENG) with a hermetic structure for harvesting multiple kinds of energies. The output performance of the A-TENG under various internal air pressures were systematically studied, which proves that A-TENG can yield a maximum output when the internal pressure is 0.5 kPa. Besides, the internal air can balance the distribution of the applied force, homogenizing the forward and reverse signals of output performance. Furthermore, the influences of different factors on the output performance were compared and analyzed. As the size of external balloon grows, the optimum internal pressure corresponding to maximum output signals shows a slight diminishing trend. By controlling the internal air pressure, applied force, frequency, air relative humidity, temperature, and external resistance at 0.5 kPa, 50 N, 5 Hz, 20%, 10 ℃, and 5 MΩ respectively, the A-TENG can generate an optimum instantaneous power density of 6.74 W/m2. Typically, constituted with fully sealed structure, the A-TENG can effectively deal with the humidity or wet environment and accommodate diverse forms of mechanical energies including mechanical pressure, wind blowing, and air vibration, etc. This work proposes a visible solution for the structural optimization of TENGs, endowed with conspicuous advantages of being simple, lightweight, flexible, and cost effective, broadening the application areas of TENGs.