With the application of deep basin theory in the Erdos basin, gas reservoirs of Upper Paleozoic were discovered continuously and reserve went up year by year. The resource of deep basin gas is one of the problems people have been always arguing about. By use of geologic theories of natural gas and Coalbed Methane (CBM) and advanced special analytical and test apparatus, through large quantities of analysis and test, this paper approved this objective fact that the rich CBM in the middle to northern part of Erdos basin is the complementary gas resource of the deep basin gas in Shan 2 and He 8 on the basis of clear geologic conditions of deep basin gas in Erdos basin.