Based on studying the volcanic rocks in Qiongaxi Valley of northern Yining County, the authors found that the volcanic rocks in thia area belong to calc-alkaline volcanic rocks strongly enriched in LREE and weakly depleted in Eu. All the samples are enriched in large-ion-lithophile elements (LILE) such as Cs, Rb, Ba, Th and U, which are ten times higher than their values in the primitive mantle. In the primitive mantle-normalized trace elements diagram, the sample shows characteristics of the island-arc volcanic rock, such as distinct depletion of Nb-Ta. However, its (Th/Nb)_N>>1 and (La/Nb)_N>>1, the ratios of Ba/Nb and La/Nb vary in a large range, Zr/Nb and Zr/Hf ratios are similar to ratios of N-MORB, and Ta/Nb ratios are similar to ratios of the upper crust, which suggests that the volcanic rocks were mixed by the lithosphere during the upward migration of the magma. All the samples point to the intermediate potassium-high potassium series, and the dominance of such a potassium type also implies that the continental crust matrix must have played an important role in the magmatic activity. The features of Zr>300 and Zr/Y>4 of all the samples show characteristics of intraplate volcanic rocks. In the diagram of Zr-Zr/Y, most samples fall into the intralate basalt region. Combined with the geological features of the study area, the authors hold that the area experienced uplifting in Devonian, and in Carboniferous the collision terminated and the evolution entered into the post-collision extension stage. Some local places produced certain rifting characteristics. Therefore, the distinct depletion of Nb and Ta might have been caused by the mixing of the lithosphere, and the environment of the Qiongaxi Valley volcanic rocks should belong to the post-collision extension phase.