Objectives: A large number of metamorphic volcanic rocks have been developed in the Balongonggaer Formation in the vicinity of Tianjun area, South Qilian Mountai.There is a lack of detailed study on the age and structural significance of rock formation. Methods:This paper takes metamorphic volcanic rocks as research objects and conducts petrology, geochemistry and chronology studies. Results:In this paper, LA-ICP-MS zircon U-Pb ages of 736±6Ma and 740±14Ma were obtained. The age was Neoproterozoic. The rock is metamorphic basalt, metamorphic quartz trachtie tuff and metamorphic rhyolite tuff. Its SiO2 content is 48.10%~53.01% and 64.14%~71.83%, belonging to the alkaline and subalkaline series, forming a bimodal volcanic rock combination.The total amount of REE of basalt is 56.3×10-6～98.9×10-6, light and heavy rare earth fractionation is medium, δEu is 0.89～1.16 with weak anomaly. The trace elements Rb, Ba, K, Sr, La, Ce, Zr, Th, etc. are enriched, and Nb, P, Ti, Y , etc.weak-medium losses.The A/CNK of metamorphic quartz trachtie tuff and metamorphic rhyolite tuff is 0.8～1.14, which has the characteristics of insufficient aluminum-excessive aluminum. The total amount of REE is 155.5×10-6～265.6×10-6, light and heavy Rare earth fractionation medium-strong, δEu is 0.63~0.94, with weak-weak anomaly. Trace elements Rb, K, Ba, La, Ce, Zr, Th, etc.are enriched, Sr, Nb, P, Ti, Yb, etc.medium-strong losses. Conclusions: Regional data, previous achievements and research in this paper indicate that the Balongonggaer Formation formed in intracontinental rift environment at the Neoproterozoic ,and it's response to the Rodinia supercontinental cleavage event.