Qiquanhe fault in Tuha basin is located in southern Qiquanhu structural belt.The sealing and open of the fault determine the oil-gas charging point and migration direction.Therefore,this fault plays a key role in formation of Qiquanhu and Yuguo oilfields.The study of the fault sealing and analysis of the crude oil geochemical parameters show that Qiquanhu fault is characterized by differential plugging by stages and sections.At the end of Cretaceous to Paleogene,the place of poor sealing could be the charging point of oil and gas migrated from the lower wall toward the upper wall.Because the source rocks of the lower wall are relatively late,in mature time,mass hydrocarbon expulsion and migration.The gradually increasing of the fault sealing in late Himalayan movement leads to the decreasing of oil-gas charging effect,so the fault open and oil-gas charging mainly happen in Paleogene.The sealing time by stages and sections of this fault determines that the oil-gas charging in Qiquanhu structural belt is local and short in time.This may be the key reason for insufficient supply of oil and gas of Jurassic from the source rocks in this area.