Abstract: The resolution and accuracy of EGM2008 is higher than any other models released in the past ten years, this corresponds to a spatial resolution of 5 arc minutes, so it is clear that high-resolution terrain model is necessary for computing high-frequency components of height anomaly and achieving higher accuracy GPS height transformation. Based on residual terrain model theory, the approach of RTM data construction and RTM height anomaly computation are discussed using SRTM and DTM2006.0 global digital terrain model. Several GPS/leveling points are selected with optimal choice method for constructing the residual height anomaly interpolated model according to their measured height anomaly, EGM2008 height anomaly and RTM height anomaly, and then the accuracy of height anomaly can be improved. Finally two cases of GPS/leveling data are adopted in this paper, and the results show that the accuracy of GPS height transformation can be obviously improved using model height anomaly computed from EGM2008 model expanded to 2160 degree and order and SRTM/DTM2006.0 residual terrain model.