Numerical simulation of continuous release and dispersion process of carbon dioxide in a ventilated room was carried out by FLUENT with Computational Fluid Dynamic (CFD) method. The validation of the simulation method was made by comparison of simulation results with experimental data. The concentration distribution of carbon dioxide indoor was investigated. The effect of the release rate, wind speed and obstacle on gas dispersion was analyzed. Results showed that at the beginning carbon dioxide moved to the top of room by the action of jet flow. Under the condition of wind, the concentration of carbon dioxide increased along the leeward. Over a period of time, the concentration of carbon dioxide indoor kept constant. Gas-detecting alarm device should be installed at the downwind position above the leaking hole. People should get away from the room before high concentration area forms. The concentration of carbon dioxide downwind decreased with increment of wind speed, while increased with increment of release rate. Vents or forced draft should be set to decrease the concentration of carbon dioxide. When there was obstacle behind the leaking source, a region of high concentration appeared in windward side of the obstacle. When designing the layout of industrial workshop, it is necessary to minimize the quantity of equipment indoor or put them near the wall, away from leakage sources. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.