Abstract: Based on infrared physics fundamentals and natural scene simulation theories, we proposed an improved system for infrared scene simulating to fulfill the real-time and accuracy requirements. Firstly, we discussed and improved zero-range-distance infrared radiation and temperature field calculation models. We reformed the empirical formulations by considering the declination of the Sun to improve the accuracy of our computation. Secondly, after we discussed the problems of positioning the heat resource and computing the heat transmission, we incorporated and took account of infrared features of different physical materials to generate high-quality rendering effects. Lastly, we used GPU to accelerate the computation for infrared emission gradation of multiple objects in various scenes. Our system is based on Unity3 D and it can construct many infrared scenes consisting of multiple objects, for instance, plants, buildings and vehicles. The comparisons of our simulation results with the authentic infrared images show the effectiveness of our system. Additionally the rendering speed of 30 frames per second can meet most basic real-time computational requirements.