Abstract: The liquid volume of A-well on an offshore production platform significantly decreased after it has been put into production.On the wellhead pressure-holding data analysis we conclude that there exists the phenomenon of tubing leakage.Considering the operation cost of the offshore oil wells , we plan to adopt the method of holding casing pressure of oil wells to maintain the high production level of the well. Through the production tests of holding pressure on-site we determine that the casing pressure be controlled at 3.4 MPa can better control leakage , and also can maintain higher submergence depth.At this time wells can normally operate with liquid production of 14.5 t / d.