Abstract: The present paper gives a detailed discussion about the lithostratigraphy, sequence stratigraphy and biostratigraphy (stromatolitic stratigraphy) of the Sailinhudong Formation in the Damaoqi region, Inner Mongolia, and separates the Sailinhudong Formation into four lithological members, seven third-order sequences and three stromatolitic assemblages. According to the existing 1:50 000 regional geological survey and mineral exploration, in reference to the previous data, especially the isotopic ages of 1456±69 Ma and 1283±59 Ma, the authors in this study contend that the Sailinhudong Formation should be traced back to the Changchengian to the Jixianian of the Mesoproterozoic.