Because of the great change in thickness of the overlying gyprock and the high density drilling fluid in Kuqa depression, it is very difficult to define the boundary stratotype. TDC are used in exploration wells and the temperature at the bottom of well can be measured continuously and the natural gas reservoirs of Eogene-Cretaceous are high pressure reservoirs. Based on this situation and according to the cause and feature of the abnormal high temperature in the natural gas reservoir, we inspected the formation temperature continuously and predicted correctly the change of the formation, defined the boundary stratotype, found the trace of gas and solved the difficulty in work.