The utility model discloses an air distribution mechanism through which a valve is difficult to deform and damage. The defect that the valve is easy to deform and damage in the conventional engine air distribution mechanism is overcome. The air distribution mechanism comprises a body, and a combustion chamber arranged in the lower part of the body, wherein the combustion chamber is connected with a plurality of air inlet channels and air outlet channels; a valve is arranged at the joint of the air inlet channels and the combustion chamber; a valve is arranged at the joint of the air outlet channels and the combustion chamber; rockers and tappets are arranged above the valves; two ends of the rockers are respectively connected with the upper ends of the valves and the upper ends of the tappets; cams which can drive the rockers to move are arranged on the rockers; and return springs are arranged on the valves. The air distribution mechanism is suitable for occasions where the conventional engine air distribution mechanism is applicable, and has the advantages that the force, deviating the valve-opening direction and stressed by the valves, can be eliminated, the service life of the valves is prolonged, and the like.