Abstract: The Yanlong bauxite deposit, which occurs in Carboniferous Benxi Formation on the Middle Ordovician erosion surface, is a typical concealed bauxite deposit in western Henan Province. The thickness of ore-bearing formation and shapes of bodies are controlled by the paleo-karst erosional surface, and are greatly influenced by structures. The dominant Al-bearing minerals include diaspore, kaolinite and illite. The upper and lower parts of the bauxitic mudstone are mainly based on kaolinite and illite respectively. The paragenetic minerals of bauxite have a great value, while the associated minerals need further study.