Abstract: Restoration of the exact thickness of eroded strata is important to rebuild the primary sedimentary and structural evolution history, the geothermal history, the history of hydrocarbon generation, expulsion, migration and accumulation, and to evaluate the potential of oil and gas resources accurately. At present, many methods have been employed in the research of the strata denudation in sedimentary basin, but each method has its own limit in application. Based on the tructural evolution research in Baijiahai arch of Junggar basin, according to the practical geological conditions and data, the method of sedimentary ratio is applied to calculate the eroded thickness of top of Cretaceous in the arch. The restoration shows that the erosion exists pervasively in Shishugou group (J2-3sh) with a relatively small intensity. The biggest thickness of erosion is near Well Block Cai-16, with the value of 280 meters.

Key words: Junggar basin, Baijiahai arch, Jurassic, eroded thickness restoration, sedimentary ratio