The invention provides a waste gas recycle device of an air intake and exhaust system and belongs to the technical field of engines. The waste gas recycle device of the air intake and exhaust system solves the technical problems that the waste gas of the engine is poorly utilized and the like. According to the waste gas recycle device of the air intake and exhaust system, the edge of a gap of a first cylinder body is connected with the edge of the gap of a second cylinder body to make an inner cavity of the first cylinder body communicate with the inner cavity of the second cylinder body; a first rotary shaft is rotationally connected in the first cylinder body and a second rotary shaft is rotationally connected in the second cylinder body; a plurality of first blocking plates are uniformly distributed on the first rotary shaft in the circumferential direction and second blocking plates which correspond one to one with the first blocking plates are uniformly distributed on the second rotary shaft in the circumferential direction; a main exhaust pipe is connected with the perimeter walls of one sides of the first cylinder body and the second cylinder body and the air outlet direction of the main exhaust pipe is located between the first rotary shaft and the second rotary shaft; a main air intake pipe is connected with the second cylinder body and located at the same side with the main exhaust pipe; the main exhaust pipe and the main air intake pipe are respectively located at the two sides of the second rotary shaft. The device has the advantages of being capable of utilizing the waste gas to save the fuel oil and the like.