The invention discloses a crossed-airway cylinder cover assembly structure of a single cylinder engine and belongs to the technical field of internal combustion engine cylinder cover parts. Air inlet passage openings and air outlet passage openings are distributed on the bottom surface of the cylinder cover in a crossed mode, two air inlet passages and two air outlet passages are distributed in the cylinder cover in a crossed mode and surround a central air sprayer, the two air outlet passages are combined in the cylinder cover and led out from the lateral surface of the cylinder cover, the two air inlet passages are led out from the same lateral surface of the cylinder cover, and swinging arms of an air inlet door and an air outlet door are fixedly installed on a swinging arm support at the top of the cylinder cover. The crossed-airway cylinder cover assembly structure solves the problem that in the prior art, air inlet passages and air outlet passages are parallelly distributed on the cylinder cover, thermal load of the air outlet passages is concentrated, interference exists in air inlet flowing and air flow mixing is insufficient, adopts the crossed airway distribution, achieves even air mixing, enables thermal load around the airways to be dispersed and stable, can effectively improve the dynamic property, economical efficiency and emission indexes of the engine and is suitable for diesel engine cylinder cover assemblies of various types.