Objective In order to solve the problem of global vertical datum unification, we integrate EIGEN-6C4 Earth gravity field model, global navigation satellite system (GNSS) /level data, and gravity anomaly data to unify local vertical datum to the global vertical datum using the geodetic boundary value problem method.

Methods To mitigate the truncation error present in Earth gravity field models, the residual terrain is converted into gravity field signals using the spatial domain method and the residual terrain model, followed by obtaining full-band gravity field information based on the remove-restore technique.

Results and Conclusions Experiments indicate that in both the United States and China regions has reached the decimeter level. Therefore, to enhance the modeling accuracy of regional gravity geoid, especially in areas with significant terrain undulations, the impact of residual terrain should be taken into account. Based on the spatial domain method and the geodetic boundary value problem method, the gravity potentials of the 1985 national height datum of China and the NAVD88 height datum are determined to be 62 636 852.749 m²/s² and 62 636 852.186 m²/s², respectively.