Abstract: Based on specified three-dimensional scene, an infrared signature simulation model for space objects was developed. Firstly, an object was geometrically modeled and decomposed into micro-elements in three-dimensions. Formulation for surface heating of the object with micro-motion dynamics from the sun and earth was derived. Energy dissipated into space from outer surface as well as the thermal exchange between facets of inner surface was calculated. In this way, three-dimensional thermal conduction of a ballistic object constructed with multi-layer materials was calculated, and the micro-element temperatures were obtained using Gauss-Seidel iteration. Then, radiant components including self-emitted radiation and surface-reflected radiation from the sun and earth in mid-long wave infrared band and long wave infrared band were calculated. It is seen that, because of the sun heating, temperature difference along the circumference is obvious when the object moves without spinning motion in space. Such difference becomes trivial when it undergoes spinning motion.