The mechanism on breakdown of chip high voltage MLCCS was researched by the analyses of the detailed experimental data. The results indicate that the electrical intensity of inner electrode sphere pile is three times of that of the plate electrode; the point electric charge density on the inner electrode sphere pile is much larger than that of the circumstance around; the air in the voids and electrode delamination, which make the effective thickness of the ceramics much less, will ionize under the high electrical filed. Three points mentioned above are the main reasons of breakdown of the MLCC. According to these results, several means are adopted to improve the producing process, which are the improving of the quality of thin films and screens, the controlling of the thickness of the electrode, the time of binder burnout, the rate of ascending temperature and the related factors, the modifying of the rate of termination paste etc. Such measures improve the dielectric strength of MLCC increase to 1.5 times of that before improving the process.