Gravity prospeting method has been one of the best way to solve geological problems. The efficiency of gravity point positioning affect the overall efficiency of the work progress, and the elevation accuracy determines the accuracy of the calculation of the gravity data processing. GPS, which can quickly obtain high-precision three-dimensional coordinates, accelerate the progress of the gravity prospecting method and improve work efficiency. RTK is the main method for gravity prospecting. But that need to set up the base station, and the further between the mobile stations and the base station, the worse of the accuracy. CORS makes up for the lack of RTK,because it can quickly survey high-precision coordinates of the WGS84 three-dimensional do not need to set up the station. The CORS system has been widely used in the fields of mapping, land, water, geological disasters, but not yet applied to the exploration of gravity. In this paper, the advantages of CORS will be discussed at first, then how to convert the results of the CORS to local coordinate system will be presented. By applying in Jiangsu 1：50 000 gravity survey, the plane accuracy is better than 1 cm, and refined quasi-geoid height accuracy is better than 5.2 cm.The accuracy meets the requirements of gravity prospecting.