The modified BaTiO3 dielectric ceramics have been prepared by different sintering methods with grain size of similar to 100 nm. The dielectric properties, core-shell structure, and the dopant distribution in ceramic grains were studied. It is found that the diffuse phase transition peak shifts to the lower temperature as the sintering process changes from conventional sintering to two-step sintering, which improves the temperature coefficient of capacitance performance at the low-temperature end. The results are beneficial to develop the ultra-thin active layer (< 1 mu m) multilayer ceramic capacitors and better control of the well-defined core-shell structures in nano-BaTiO3 grains to maintain the temperature stability.