The invention discloses a swing piston internal combustion engine structure, and relates to the field of power machines. A swing piston power machine is mainly composed of the components such as an air cylinder, a swing piston, a swinging plate, a main shaft, a swash plate, a spark plug and an intake and exhaust system; the swing piston is mounted in the air cylinder, and is mutually matched with the inner surface of the air cylinder to form four working chambers; along with the swing of the swing piston, the volumes of the working chambers change periodically, and the four strokes of air suction, compression, acting and air exhaust are completed; the swing piston is connected with the main shaft through the swash plate, and mutual conversion between the swing of the piston and the rotation of the main shaft is completed. The swing piston power machine has the advantages of simple and compact structure, large power density, small friction, high operational reliability and efficiency and the like.