Abstract: Based on core and logging data, a bed response model of datum level cycle for Tengor Fm in Baorao low land in Jirgalangtu sag is built by using the principles and methods of high resolution sequence stratigraphy. Three long -term datum cycles (third grade sequence), including LSC1, LSC2 and LSC3 are identified in the Tengor Fm through comprehensive analysis of drilling, logging and 3D seismic data and a high resolution isochronic strati-graphic framework is built for Tengor Fm. The intrinsic relationship between datum level cycle and the pattern of sandbody development is studied in the context of the i-sochronic stratigraphic framework.