Abstract: To establish the modern geodetic datum of China,the characteristics of modern geodesy and the practice of China should be taken into account simultaneously.So the following four factors should be focused on especially:high accuracy,covering all of the territory including land and ocean,three dimension,and dynamic.Establishing the modern geodetic datum is to supply a reliable and proper basic frame of the geographic space for users anytime and anywhere,and its task should include the establishment of planar datum,height datum and gravity datum.