Xilinhot-Abaga volcanic cluster is located in Xilin Gol League of Inner Mongolia, and it is in the centre of the Greater Hinggan Mountains-Datong volcanic eruption belt. There are more than 300 Quaternary basaltic volcanoes of different types. Maars are found there,with Haotewula in the southeast of Abaga Banner, Chelewula and Esigewula in the northwest of Abaga Banner being the most repre sentative. They have relatively intact structure, similar two ringed mountain landscape and obvious phreasic eruption which contains strong phreatomagmatic eruption at the earlier stage,later weak magmatic eruption and at last basaltic lava overflowing phase. This eruption sequence reflects the interaction between magma and groundwater,the change in intrusive speed and the flowout rate of magma. The sand and gravel of Middle Pleistocene depositing in the valley are covered by basal surge deposits. The TL age of sandstoneshale inclusion which was found in the spattering deposits close to crater is (0.112± 0.009 6) Ma,which indicates that the eruption times of the maars are early Late Pleistocene.