In china and abroad, the alkali feldspar granite is generally characteristic of polymetallic mineralization, especially the rare metal mineralization. In china, this kind of mineralized intrusions are mostly distributed in the South China fold system. The Dongqiyishan alkali feldspar granite in the western Inner Mongolia is a large rare metal mineralized rock body in the northern area of China, where this kind of intrusion is infrequent. Because of lacking former researches, the understanding on it is somewhat superficial. Based on the few former research, this paper performed a lot of deep and detailed work on its lithology, metallogeny and the mechanism of its petrogenesis and mineralization. It shows that the intrusion is a alkali feldspar granite rock body formed by direct differential evolution of the crust-derived magma. Besides rubidium, the Nb-Ta contained in the rock also has considerable value in use. Furthermore, The alkali feldspar granite is the source of the tungsten, tin and beryllium resources. The large fluorite deposit and Aragonite-calcite deposit derived from the intrusion also has extremely high economic values. This can greatly improve the practice and theory of the petrogenesis and mineralization of the Dongqiyishan alkali feldspar granite. It also has great implication for guiding regional prospecting ore deposits related with this kind of intrusions.