Abstract: Height transfer from land to island is of significance for accurate surveying of islands. An approach based on GNSS and EGM2008 to height transfer is proposed. After introducing the basic principles, the formulas for calculating the mean gravity by the gravitation potential model are presented and the possible error sources on this method are analyzed. Errors generated by the gravitation potential model are the main factor that affects the accuracy of a calculated height. Tests using GNSS/leveling data for mainland and islands of China, and in US show that height accuracy better than 10 cm over a distance of 200km is achievable for land areas and 6 cm over a distance of 10 km for islands.