BaTiO3-based ultrafine nonreducible dielectrics for multilayer ceramic capacitors were prepared by a newly developed nanocomposite doping process. According to TG-DTA, XRD and TEM analysis, the nanocomposite dopants via sol-gel method were uniform and well dispersive. The micromechanism was investigated based on comparing conventional process with nano-doping process. It indicated that due to the special nano-effect, doping effect of additives became more effective and the microstructure and dielectric properties of ceramics were improved. The results showed that high performance dielectrics satisfying X8R specification were achieved, with high dielectric constant of 2,900, low dielectric loss of 0.6% and large insulation resistivity of 10(12) Omega cm.