Abstract: The volcanic rocks of the Tanjianshan Group in the Buhete Mountain area in the northern margin of Qaidam Basin are mainly calc alkaline, with a small amount of tholeiitic trend, and the lithology is mainly andesite; The main element has the characteristic of low Ti（with an average value of TiO2 less than 1%）; Rare earth elements are enriched with light rare earth elements, characterized by significant negative Eu anomalies; On the spider web diagram of trace elements, the sample shows enrichment of large ion lithophile elements, loss of high field strength elements, and obvious "grooves" in Nb and Ta. It shows that it was formed in an island arc environment.