In order to study the influence of structural factors on the separation performance of labyrinth oilgas separator used in a new type of 6cylinder natural gas engine, 7 groups of different structural combinations were designed, the influence of structural parameters on separation efficiency was compared and analyzed by the control variable method, and the structural parameters with greater influence on the separation efficiency were preliminarily investigated. The experimental results show that the effect of the number of through holes in the coarse filter plate and the distance between the coarse filter plate and the baffle on the separation efficiency is greater than the diameter of through hole, wherein the influence of the number change of through holes on separation efficiency is the most obvious. The separation efficiency increases by 11.6% when the number of coarse filter holes reduces by 6, while the separation efficiency increases by 12.4% when the number of fine filter holes reduces by 4.The fact that the diameter and the number change of fine filter holes are both smaller compared with coarse filter holes but the fine filter can get larger separation efficiency increase amplitude indicates that the influence of the number change of fine filter holes on the separation efficiency is greater than that of coarse filter holes. For the fine filter orifice plate, the effective separation of tinydiameter oil droplets becomes the key to improve separation efficiency.