On the basis of the work that the regional geological survey of Jiaolai basin southern margin was carried, the stratotype section for the volcanic rocks of Cretaceous Qingshan group in study area was measured with system sampling. It was showed that the content of SiO2 in the volcanic rocks of Cretaceous Qingshan group is about 51.08%-74.86%, total alkalis is about 3.2%-8.8%, Al2O3 is about 13.18%-17.3%, and TFe2O3 is about 0.86%-10.48%, after chemical analysis and data processing. The character of trace and rare earth element is that La and Nd which are LILE and LREE are relatively enriched, while Nb, P and Ti which are HFSE and HREE are relatively loss. Houkuang and Shiqianzhuang formation have the similar geochemical characteristics that the volcanic rocks are mainly composed of acidic rocks, while Bamudi and Fanggezhuang formation have the similar geochemical characteristics that the volcanic rocks are mainly composed of intermediate rocks. The volcanic rocks of Bamudi and Fanggezhuang formation that erupted lately have more total alkalis than that of Houkuang and Shiqianzhuang formation. The result of comprehensive analysis was that the volcanic rocks of Cretaceous Qingshan group in Jiaolai basin southern margin were intermediate-acidic rocks with peraluminous, K-rich and calc-alkaline characteristic. The magma source of the volcanic rocks that erupted in four different episodes was the same——the lower crust, the reason of which may be related with subduction of Yangtze plate. Magma evolution process of the volcanic rocks showed strong crystal fractionation.