Abstract:In this paper, the determination methods of vertical deflection, including numerical fitting, GNSS leveling, Earth gravity field model, and numerical fitting based on remove-restore technique, are investigated. The experiment is conducted using a high precision data set of GNSS leveling and vertical deflection from the project of the geoid slope validation survey of 2011(GSVS2011). The results show that numerical fitting, Earth gravity field model, and numerical fitting based on remove-restore technique have good fitting accuracy, that the Biharmonic (v4) method from numerical fitting model has better fitting accuracy, and that fitting accuracy can be improved based on the remove-restore technique. However, the accuracy of the GNSS leveling method is relatively poor.