Based on the 1:50000 regional geological survey and the triple mapping method of "volcanic tectonic-lithologic lithofacies-volcanic stratigraphy", the volcanic rocks of the Baiyingaolao Formation in Sangjie Aobao area, East Wuqi, Inner Mongolia, are divided into three lithologic segments, namely, pyroclastic sedimentary rocks, acid volcanic rocks and neutral volcanic rocks, which constitute a complete sediment-eruption cycle. The magma evolved from acidic to neutral from early to late period. Volcanic sedimentary facies, cave-down accumulation facies, overflow facies and volcanic channels were developed, and six V-class volcanic structures were delineated. Based on LA-ICP-MS zircon U-Pb isotope dating, it is determined that the second member rhyolite of Baiyingaolao Formation in Sanjie Aobo was formed in 134.95±0.99 Ma, and the age is Early Cretaceous. Geochemical characteristics show that the main element SiO2 content ranges from 69.56% to 71.11%, K2O content ranges from 3.96% to 4.39%, K2O/Na2O value ranges from 0.69 to 1.03, and A/CNK value ranges from 0.97 to 1.07. The volcanic rocks of Baiyingaoao Formation in Sanjie Aobo belong to the high potassium calc-alkaline series. Rb, K, Th, U are relatively enriched, Sr, Ti, Nb, Ta, P are relatively depleted, and the difference of heavy and heavy rare earths is obvious, and the former is higher than the latter, and the standardized partition curve of rare earth elements chondrites shows A right-leaning "seagull", which conforms to the geochemical characteristics of A-type granite. Combined with previous studies and data analysis, the volcanic rocks of Baiyingaolao formation in Sanjie Aobao should be formed in the post-orogenic extensional tectonic environment. Therefore, the determination of the volcanic rocks of the Baiyin Gaolao Formation in this study area provides petrological, chronological and geochemical constraints on the stratigraphic sequence and tectonic setting of the Mesozoic volcanic rocks in the eastern part of the Central Asian orogenic belt.