Abstract: Aiming at the high exhaust gas emission of underground vehicles in coal mines, through the analysis of the working principle and structure of road three-way catalyst, the Canadian DCL type three-way catalyst was selected, and then according to the requirements of China’s coal industry MT 990 - 2006 Mine Explosion-proof Diesel Engine General Technical Conditions, the three-way catalyst was designed and modified by explosion-proof water cooling, and then two kinds of layout methods were adopted finally, the whole vehicle was tested on the wc55y (b) bracket truck. The results show that: the surface temperature of the three-way catalyst after explosion-proof modification is lower than 150 ℃, which meets the requirements of MT 990 - 2006; the CO and HC emissions of explosion-proof vehicles after the application of water-cooled explosion-proof three-way catalyst are obviously reduced.