The Permian Lower Urho Formation overlapped layer by layer in the Block 8 of Karamay Oilfield, Junggar Basin. It suffered from intense denudation because of the late strong thrusting and uplifting. Therefore,resuming stratum palaeothickness not only can rebuild the burial and evolution history of the study area,but also is an important base of quantitative estimation of petroleum resources. However,traditional calculation method of denudation thickness is constrained by low degree of exploration. According to actual data and geological conditions of the study area,a suite of quantitative calculation method is probed out. Based on a new way of seismic trend thickness integrated with sedimentary sequences analysis,denudation boundary of the Permian Lower Urho Formation has been outlined. A composite method of the thickness ratio of nearby layers and the change ratio of reference layer thickness have been applied in calculating true denudation thickness of the Member 3 of Lower Urho Formation. By analyzing evolution characteristics of the Member 3 of Lower Urho Formation in the key sedimentary periods,a sedimentary model of fan delta has been established in the study area. The distribution range of delta front subfacies is also depicted at the same time,which can provide reliable geological evidence for the future petroleum exploration.