In order to improve the cooling & purifying effect of exhaust, reducing the water-jetting phenomenon during working time, the waste-gas flow field simulation in water-washing tank of Explosion-Proof Diesel (EPD) was conducted through ANSYSCFX/Fluent. The results revealed the inner flow condition and outlet temperature of emissions in water-washing tank. It provided a reference for the future design and optimization of the water-washing tank of EPD.