In order to study infrared radiation characteristics of fume released from the tank,the numerical calculation model of flow field for tank fume is established,then the flow field distribution is analyzed and calculated,so the temperature field distribution is gained.The radiance of fume is worked out by using C-G approximate model of channel bands and the thermal image simulation is completed.The radiance of carbon dioxide is computed and compared with the test value.The result shows that the model and the method can be used in the application of the infrared thermal image simulation.