Gravity glide thrust fault is always a significant type of thrust fault in the extensional basin. The research on it is of great significance for its playing an important role in hydrocarbon migration and accumulation, being one of the major targets of oil and gas exploration. Through finely analyzing Paleogene structure of Wangguantun region in Huanghua sag, specially re-analyzing the particular fault, utilizing kinematic equilibrium rule and analyzing the thrust fault developing process, I found there were discrepancies in predecessors′ interpretation to the thrust fault in the area: this fault did not form during the late period. It formed from a slump fault with small growth rate whose fault section dip changed mild, even level because of depocenter migration. The fault was pushed by the force of gravity so that the hanging wall slid along the fault plane, and makes the scan finally in the late revealed the nature of a thrust fault. Although the shape of these faults is very similar with the thrust fault formed late in previous view (early growth coefficient is small, displacement had little change), there are huge differences on origin of these two faults whose petroleum geological significance is quite different. This study is very significant to the structure research of the region and the other similar regions, providing the new theory for oil exploration.