Ceramic sintering in microwave field is a new ceramic processing method. In present paper, we detected the microstructures and boundary segregation of BaTiO3 ceramics which were sintered in microwave field. Scanning electron microscopy(SEM), and transmission electron microscopy(TEM), and chemical analysis methods were employed to detect the microstructure of BaTiO3, element distribution near the boundary of BaTiO3 ceramic. The results shown growth of grain of the ceramic was influenced by impurities such as acceptor, benefactor et al, and the element distribution near the grain boundary of BaTiO3 sintered in microwave field were different with that sintered in conventional method. The boundary segregations of BaTiO3 sintered in microwave field were not obvious as compared to the conventional method because the diffusion was enhanced due to the microwave field.