Abstract: Microstructure evolution of polycrystalline materials plays an important role on properties of materials. 3D modeling of microstructures of polycrystalline materials is implemented using Monte Carlo Potts-model simulation. The modeling includes many microstructural parameters, such as grain size and grain size distribution, grain shape, grain orientation, properties of grain and grain boundary. Three-dimensional visualization of so-constructed microstructures is further carried out. The results show that these models can simulate polycrystalline microstructures with various parameters, and can be used as meso-scale models of numeric simulations of processes and of meso-mechanics computation for polycrystalline materials.