Abstract: Drilling fluid is critical for exploration and development of shale oil/gas and conventional oil/gas in complex reservoirs.In this paper,Sinopec’s research and application of oil-based drilling fluid in recent years were introduced in several aspects,such as technical difficulties,R D of key agents,development of diesel oil or mineral oil based drilling fluid system,and supporting processes and techniques.Moreover,future development of such techniques in Sinopec was discussed based on the comparison of oil-based drilling fluid techniques in China and abroad,and technical demand.