Abstract: Lunar geoid (or selenoid) anomaly and topogrphy variations are the expressions of its internal density anomaly and boundary undulations. So the geoid to topography ratio (GTR) can be used to study the isostatic state of the Moon and its crustal thickness. In this paper a new lunar crustal thickness model is derived by GTR technique from filtered gravity model SGM100h and topography model STM359_grid-02, with the mare fill removed. This model indicate that the lunar crust has an average thickness of 36.9 km, and the average farside thickness is 13.5km thicker than nearside. The crustal thicknesses at Apollo 12/14 sites of our crustal thickness model are 28.3 and 29.1 km, respectively. It also shows that the crust beneath the mare basins is generally thinner than the regions around.