Abstract: The Nannihu molybdenum deposit, located in Luanchuan County, Henan Province, covering an area of 3.98 km², is one of the supper-large-sized molybdenum deposits in the world. Based on the study of regional geology, orebody characters and metallogenic conditions, as well as the relationship between the metallogenesis and the structural belt, small rock body and wallrock alteration, it is concluded that the Nannihu molybdenum deposit is genetically controlled by the structure, wallrocks and their alterations, and closely related to the middle Yanshanian porphyry monzogranite. Prospecting in the deep and surroundings of the orefield is promising.