The spatial distribution of geological features is closely related to the geological background of the rock and soil mass. 3D geological modelling is a core component in Digital Earth and intelligent geotechnics fields. Currently, the spatial interpolation methods commonly used in 3D geological modelling software, both domestically and internationally, predominantly rely on purely mathematical interpolation techniques. These methods often fail to adequately account for the objective geological background, compromising the accuracy of 3D geological model construction. A novel interpolation method, termed the Correlation-Weighted Interpolation Method, was developed by incorporating the influence of geological background through the correlation distance in random fields. The correlation distance was employed to define the interpolation neighbourhood and weights in the traditional inverse distance weighting (IDW) method. Case studies demonstrate that the Correlation-Weighted Interpolation Method effectively reflects geological background features, enabling geological modelling that aligns more closely with actual geological conditions.