Abstract: Focusing on 200 mm silicon epitaxy preparation technology for BCD devices, based on the properties of epitaxial layer such as pattern shift, uniformity and surface defects, the influencing factors of the process such as concentration of buried dopant, deposition temperature, growth rate, structure of buffer layer were analyzed and the preparation technology was optimized.At last, the 200 mm Si epitaxial wafer for the BCD process was prepared by CVD method and the properties of the epitaxial layer were evaluated by Hg-CV, SP1 and SRP.The experimental results were in according with the process design results which improved the mass production of silicon buried layer epitaxial wafer for BCD process.