Abstract: Qingtashan rock mass is located in the western section of East Kunlun, and the formation age, environment and rock type of the rock mass are still controversial, with low research degree of the physicochemical conditions during the process of rock formation and its source characteristics. On the basis of systematic lithology and petrographic research, the authors in this paper conducted composition analysis on the main rock-forming minerals such as biotites, plagioclases and hornblendes. The physicochemical conditions during the process of rock formation were identified and petrogenesis of the rock was further constrained. This study shows that the lithology of Qingtashan rock mass is tonalites, and the lithology of the dike is quartz-diorites. The Plagioclase feldspar in the rock mass is andesine and labradorite, the biotite is magnesiobiotite, and the hornblende is magnesiohornblende. An anti-zoning band was developed in the plagioclase, which was caused by magma mixing. The crystallization temperature is 684~693 ℃ and the crystallization pressure is (1.86~2.01)×10⁸ Pa, with average value of 1.92×10⁸ Pa. The corresponding crystallization depth is 6.90~7.46 km, with an average of 7.12 km, belonging to the medium-deep formation phase. The oxygen fugitivity during rock mass formation is low, which is between -17.34 and -17.04. The mineral chemical characteristics show that the material source of the biotite in Qingtashan rock mass is calc-alkaline orogenic suite, and its formation is related to the crust-mantle mixed source magmatic. This study could provide references for the evolution of Late Triassic-Early Jurassic magma in this region.