Taking Kongqueting area of Xihu Sag in East China Sea as the research object, referring to previous research results, the fault sealing property is quantitatively evaluated based on the regional geological condition, by calculating the dip of fault and the positive sectional pressure, combining with the shale content of fault zone, and calculating the fault sealing index. The result shows that the best sealing is the Fault Muyi and the worse is Fault Kongyi. From the high zone to the low zone, the positive sectional pressure increases due to the influence of burial depth and the fracture sealing index increases gradually. There are differences between different faults and different parts of the same fault, which are mainly affected by the dip of fault, fault distance, fault strike and the content of mud in fault zone. Today's hydrocarbon display can be used as an effective basis for judging fault sealing. Combined with the characteristics of fault sealing index, the lower limit of oil and gas fault sealing index in this area is finally determined to be 8.0. The study on the relationship between fault sealing and hydrocarbon characteristics in Kongqueting area can provide reference for subsequent trap evaluation in the next well location target.