The invention discloses an air cylinder rotor type internal combustion engine. The air cylinder rotor type internal combustion engine is characterized by comprising a left bearing cover, an engine body, a rotor, a cylinder body, a piston, a right end cover, a right bearing cover, a left end cover, a rolling bearing A, a rolling bearing B, a planet gear, a sun gear, a rolling bearing C, a rolling bearing D, a gas valve, a sparking plug and a gas valve switch. After improvement, the inner part of a cylindrical cavity of the engine body is separated into two semi-annular cavities through left and right separation walls on a middle plane; an upper cavity is connected with a gas inlet pipe and a lower cavity is connected with an exhaust pipe, so that intake and exhaust are separated and an overlapping angle of the intake and the exhaust is eliminated; and residual waste gas is reduced to the lowest level so that combustion conditions are improved and emission pollution is reduced.