Abstract: Based on the application of DGPS in GT?1A airborne gravity measurement system, the authors discussed the selection and precision of GPS stations, and analyzed a variety of calculated free air anomaly results in detail. The final results indicate that the dif?ferent values of GPS basic station position induces the horizontal error of free air anomaly on survey lines, and the results on the same survey line can almost reach the same precision after horizontal adjustments. In addition, the distances between GPS basic stations and rover stations have impacts on the locally detailed amplitudes of free air anomaly. After horizontal adjustments, the internal accord accu?racy on the same survey line can reach almost 0.3.