Abstract：The Pleistocene strata with stable regional extension in the southeast Inner Mongolia are divided by pollen assemblages and optically stimulated luminescence (OSL) dating. The eolian sediment of the middle Pleistocene with good columnar joint and OSL age from (40.4±1.9)ka to (110.0±7.5)ka, corresponding to the Wuerji Formation, is composed of yellow sandy loam, calcareous nodule and Artemisia-Ephedra-Pinus pollen assemblages. The lower Pleistocene with OSL age from (200.9±9.6)ka to (220.4±13.2)ka, corresponding to the Chifeng Loess, is composed of reddish brown sandy loam, sandy clay, calcareous nodule, gravel lens and Artemisia-Polygonum-Betula pollen assemblages. These provide basic data for Quaternary stratigraphic correlation and division in the southeast Inner Mongolia.
