Abstract: The major advances in the study of Mesoproterozoic isotopic geochronology in the aspects of stratigraphy and thermo-tectonic events as well as their geological significance since the 3rd Stratigraphic Congress of China held in 2000 are described in this paper.It is pointed out that the establishment of a type stratiraphic section of the upper Mesoproterozoic and the revision of the Mesoproterozoic time scale of China are the main new key problems at present.