Abstract:Separating off different gravity anomalies is the key to reasonable gravity data interpretation.Optimal filtering for separating off different gravity anomalies is described detailedly.Particularly,the paper details the principle and applicable conditions of Wenner filtering,and offers formulae of weight coefficient,correlation radies corresponding to frequency character *and average amplitude of gravity anomalies.The theoretical gravity anomalies of several combined models are computed accurately.It is shown that different gravity anomalies can be separated off by using the correlation radius method of Wenner filtering after estimating the correlation radii and average amplitudes of different gravity anomalies on the basis of prior statistical analysis.This technique was used to separate off the observed gravity anomalies within D district in North China.The resultant basement anomaly reflects correctly the shape of intermountain sedimentary basin,and the local anomaly mirrors clearly the local landform undulation in the basin.