Abstract: Based on the theory of site displacement due to ocean tide loading,the site displacements of some IGS(International GPS Service) stations resulted from ocean tide loading were computed respectively using the data given by the Onsala Space Observatory of Sweden and the National Astronomical Observatory of Japan,and comparied in order to select a proper ocean tide model and ocean tide wave number to enhance the GPS(global positioning system) positioning.The comparison shows that to an oceanic or inland IGS station the difference between the two types of corrections is unremarkable,but to a coastal IGS station,the difference is remarkable.So it was believed that in GPS precise positioning,the corrections of site displacements resulted from ocean tide loading should be considered sufficiently,and the feasible selections of ocean tide models and ocean tide wave numbers are important so as to improve the accuracy of the corrections.