Abstract:Er'lian basin group is the biggest late Mesozoic basin group in Inner Mongolia, and Duhumu basin is one of the basins which are rich in coal resources. Coalbearing strata are located in the fifth section of Cretaceous Yanhua formation. Coal quality is lignite with mellow lime, high sulfur, high calorific value, lowmedium phosphorus and low chloride. Structures in this area are very simple. Saihantala coal field which is controlled by HaolaiXilinhuduge fault has been naturally divided into several coal accumulating basins with unequal scale. Magmatic rocks in the marginal areas of this basin developed well. It is mainly composed of intrusive rocks in late Variscan and early Yanshan period. Its rock property is superbasic to acid, and generally occurred as county rocks. Coal strata were formed by the sedimentary combination type which was controlled by flooding and the sedimentary facies based on shallow water gravity flow and peat swap sediments. Sedimentary environment can control the distribution of rich coal belt. The main coal accumulation occurred in late basin developing period. The coalrich belt was located in the northwest side of the basincontrolling fault with the distance of 2~4km.