Abstract: A kind of new methed,which is GPS tidal level measurement,is presented for the determination of instantaneous tidal level at the vessel.The data processing procedure includes the time otfset correction,attitude correction,quality control of GPS height;fusion of GPS height and heave,draft correction,and the filter of GPS tidal level.After these processing, precise tidal level at vessel is determined finally,and the new inethod is also praved by few experiments.