Abstract: Starting from the law of error propagation and total differential theory, on the basis of comprehensively considering the horizontal position error and elevation error of gravity measurement points and terrain DEM, an objective and effective method for evaluating the accuracy of terrain correction in mid-gravity region based on DEM data has proposed.Through theoretical model research, it is believed that the gravity terrain correction value and its error have a positive correlation with the terrain correction radius,with the increase of the ground modification radius, the ground modification value and its error growth rate become smaller; the elevation error has a greater contribution to the terrain correction error than the horizontal position error, and the mean square error of the terrain correction is mainly composed of the elevation error; the DEM resolution has a great influence on the terrain correction error, especially the DEM with higher precision and resolution should be selected in the relatively near area.The calculation of the actual data in the Qinling Mountains proves that the terrain correction accuracy evaluated by this method is similar to the requirements of the current specification, which overcomes the false high accuracy of terrain correction in the past; the 1∶10,000 DEM data can fully meet the requirements of terrain correction in the middle area of the 1∶50,000 gravity survey, and can basically meet the needs of the 1∶10,000 ～ 1∶25,000 gravity survey; if a 1∶50,000 terrain DEM is used to correct the terrain in the middle area of the 1∶50,000 gravity survey, the starting radius should be greater than 300 meters.