Abstract: Abstract：The main purpose of this fundamental research is to reunderstand Late Jurassic Manketou Obo Formation and Early Cretaceous Manitu Formation as well as Baiyingaolao Formation in Huiyin Obo area of Dong Ujimqin Banner, Inner Mongolia. Several sets of experiments were carried out to test the validity of the ages of three formations; these formations are comparable with Chagannuoer Formation and Bulagehada Formation from “1∶250000 Regional Geology Survey in Hesigewula Farm”. On such a basis, the authors have reached the conclusion that further research into the Mesozoic volcanic rocks in Huiyin Obo is necessary.