Abstract: On the basis of the principles of sedimentology, using the data of field measurements on the diameters of gravels of different facies in modern diluvial fans in the areas of Changma and Kuantai on Hexi Corridor, and the statistical data for the trend of thickness variation of sandy conglomerates in Jixi area versus facies belts, the exponential equations for the relations between mean diameter of gravels and the thickness of sandy conglomerates with transportation distanceare etablished. The two equations and the trend of the strike of isopaches of the Cretaceous were applied to restoring the original sedimentary boundaries of the Cretaceous deformed basin in northern margin of Qilian Mountain, Jixiarea.