1. College of Geo-Exploration Science and Technology, Jilin University, Changchun 130026, China;
2. 519 Team of North China Geological Exploration Bureau, Baoding 071051, Hebei, China

Gravity data observed in geophysical surveys are the sum of potential field produced by all underground inhomogeneous geological sources with different scales, different patterns and different depths. The aim of gravity exploration is mainly to extract the meaningful local anomaly from the regional gravity anomaly which is helpful to detect the deep structure and delineate the favorable area for mineral prospecting. In this paper, several anomaly separation methods are theoretically discussed, including trend analysis method, finite element method, interpolating cut method and analytic continuation method. And, these methods are applied to achieve the delineation of potash-mine deposit in Vientiane. Through experiments, analysis and comparison, the separating result of upward continuation is shown to be satisfactory, for that can separate the ore body anomaly from the background field more effectively. Further, with the combination of the geological information and gravity anomaly, it infers four rich potash zones in the study area of Vientiane which is significant for future geological work.