Geological work is an eternal enterprise, geological map is the carrier and concentrated reflection of geological work achievements. It can not only provide basic geological data for exploration and evaluation of the mineral resources, geological environment and geological hazards, but also opens the way for the innovation of geological science theory. This paper cites some discussion about the importance of geological map that come from famous scientists and the geological departments and summarizes ten major functions of geological maps: reflects a country’s level of geological scientific and technological and the geological research degree; records of the development of geological history; provides the geological background information for mineral exploration and potential evaluation; provides a scientific basis for the optimization of geological environment and prevention of geological disasters; opens the way for the innovation of geological science theory; provide empirical data to safeguard national sovereignty and interests; promote international cooperation and exchanges in geoscience; popularization of scientific knowledge; Training high level of regional geological talent; Being the essential data to achieve scientific management for geological work.