Abstract: A new image simulation algorithm for three-dimensional grain growth of polycrystalline materials is built．The algorithm is simple in structure and flexible in application．Comparing to the old algorithm，the present method not only has obvious physical meaning，but also improves the simulation efficiency prominently．The algorithm can be conveniently applied to observe microstructure and its evolution in materials on horizontal sections，as well as sections at certain angle to the horizontal plane，and can also be used in such quantitative analysis as kinetics and topology of three-dimensional grain growth．