The invention relates to a small airplane air conditioner compressor installation device. The small airplane air conditioner compressor installation device comprises a supporting base fixedly installed on a left casing of an engine, a single supporting arm installed on an engine support lug, and a tensioning device. The end portions of the supporting base and the single supporting arm are both fixedly connected with a compressor. Stable three-point supporting is achieved for the compressor through the single supporting arm, a left supporting arm on the supporting base and a right supporting arm on the supporting base together, and therefore the compressor can reliably and stably work, and the compressor is prevented from twisting during operation; and after a regulation nut of the small airplane air conditioner compressor installation device is loosened, a tensioning wheel rotating shaft is rocked and turned by a certain angle so that a V belt can be tensioned or loosened through a tensioning wheel, tensioning force regulation is achieved, compensation for V belt datum length changes caused by friction heat deformation and mechanical vibration deformation is regularly achieved, anddetachment and installation are convenient. The small airplane air conditioner compressor installation device is simple in structure and accurate in transmission.