Abstract: The Luokuidong molybdenum deposit in Hainan Province, occurring in and around the contact between continental volcanic rocks and concealed porphyraceous granite, is of a large sized porphyry-type one. The deposit is concealed, with rare molybdenum mineralization outcrop in the surface. The most common alterations in the orefield are silicification and pyritization, followed by potassic alteration, sericitization, phyllic alteration, greisenization, illidromica alteration, biotitization, epidotization, uralitization, chloritization and carbonation, locally with pyrophyllitization and fluoritization, among which, the silicification, potassic alteration, phyllic alteration and greisenization are closely related to the molybdenum mineralization. Preliminary study shows that, outwards from the central crater facies, the alterations in the area can be roughly divided into four unclear zones:strongly silicified alteration zone, siliceous and potassic alteration zone, silicified alteration zone and epidotization-chloritization zone. In the detailed survey work, the scope of mineralization can be determined by the silicified veinlets on the surface. The areas with strong potassic alteration are always the Mo-enriched positions.