Abstract:To improve the accuracy of quasigeoid/geoid determination based on GPS/leveling, we present a new approach to fit quasigeoid/geoid called semi-free position point mass, based on the gravity field approximation principle. Compared with the traditional point mass model, the plan coordinates of the new model are stationary, while the depths are free. The method is established by a kind of iterative algorithm using the relationship between the nearest points. The gravity parameters are fitted in multi-band by several mass-points under the known data-points with different depths. Three experiments are conducted in different test zones where the data conditions vary. The results show that applying the model to quasigeoid/geoid fitting is feasible, and achieves higher accuracy than Kriging and Co-Kriging method in the test zones.