Fluent software was used to simulate the wind flow state and CO diffusion in submerged arc furnace during collapse, where a three dimensional k ~ ε model was adopted, and the effect of buoyancy was taken into consideration. The simulation results show that wind flow for each respiratory surface can be divided into three zones, namely, mainstream zone, eddy zone and stagnation zone. Eddy zones appear at chimney sites while stagnation zones can be found at the wall of mainstream outlet. From the analysis of CO diffusion and distribution at different wind velocities and directions, it can be concluded that CO concentration decreases from eddy center to periphery driven by mainstream entrainment. Regression analysis shows that ventilation time decreases exponentially with wind speed increase.