Abstract: Changshan molybdenum deposit is located in Qimantage area of western East Kunlun of Qinghai province. In the past, Changshan deposit was a contact metasomatic iron deposit. Recently, some granite porphyries and porphyry molybdenum mines have been found, which has great significance for metallogenic study and mineral exploration of Qimantage area. Based on studying distribution, rock types, petrology and petrochemistry of intrusive rocks, the result has been achieved as follows. These granite porphyries are some apophyses intruded into porphyritic monzogranite. The outcrop area of granite porphyries is less than 0.01 km² and the biggest thickness are 30 meters. These rocks have the features of higher SiO₂ content, lower TiO₂ content, bigger ratio of K₂O and Na₂O, higher differentiation and lower consolidation. They are similar with potassic calc alkaline granite and mineralization porphyry rocks of Tibet Gangdise in petrochemistry feature, except for the higher SiO₂ and the lower Al₂O₃. They are possibly related to extension of post-collision tectonic. The genesis of Changshan molybdenum deposit is considered as porphyry-type. There are better prospecting potential in mid-west Changshan deposit and Qimantage region.