Abstract: To study the influence of the waste gas treatment tank of explosion-proof diesel engine structure on the exhaust cooling effect, two dimensional internal two-phase flow models are established for the waste gas treatment tank with two different structures, they are equipped with baffle and without baffle. The software Fluent is used to simulate two models in order to study the cooling performance and pressure loss. The simulation analysis of four kinds of different size baffle is carried out to study the effect of baffle on cooling performance and pressure drop of waste gas treatment tank. The results show that the cooling effect of final exhaust temperature is very good after installing baffle with proper width for waste gas treatment tank it meets the design requirement of waste gas treatment tank, but it will increase the overall pressure drop of waste gas treatment tank. In order to ensure the final exhaust temperature of waste gas treatment tank to meet the design requirement, the total pressure drop is the lowest when the exhaust gas treatment tank has the baffle with a width of 6 mm, it has the least influence on the comprehensive performance of the explosion-proof diesel engine.