The Nanbaishuihe Formation of the Jixian System is a basement series in the western part of the Central Qilian Block, which is of great significance to the study of Proterozoic geological structure evolution of the Central Qilian Block. The author discovered basaltic andesite interlayer in Nanbaishuihe Formation through 1: 50,000 regional survey, Zircon U- Pb chronology and petrogeochemistry of the basaltic andesite have been studied in this paper. The dating results show that the formation age of basaltic andesite is 1489±16 Ma, which belongs to the Changcheng Period of Mesoproterozoic, and the successor zircon age is 1926 ~ 2053 Ma, which is the geological record of the Columbia supercontinent convergence event. The geochemical analysis of the rocks shows that the geochemistry of the rocks is rich in Na2O, FeOT, Al2O3 and poor in TiO2 and K2O. The rare earth partition curve is right- leaning light rare earth enrichment type, LREE/HREE=3.73~6.72. (La/Yb)N is 5.66~7.56,δEu= 0.69~0.81, and large ionic lithophile elements such as Ba, Th, U, and Nb are enriched, while Nb, K, P and Ti are relatively depleted, which has the characteristics of alkaline basalt in the plate and is the product of stretching mechanism. It is a response to the breakup event of the Columbia supercontinent in the early Middle Proterozoic of the Qilian Block.