Abstract: Based on the flexural isostasy model of the lithosphere, a 1°×1° model of lithospheric effective elastic thickness over the global seafloor was calculated by the Moving Window Admittance Technique (MWAT) method, using bathymetry and gravity anomalies derived from altimetry data. The results show that the lithospheric effective elastic thickness over the seafloor is generally small. About 70% of the seafloor has an effective elastic thickness of lower than 10 km, and 85.4% are lower than 15 km. The mean and standard deviation of effective elastic thickness is about 10 km and 6.7 km, respectively. The lithosphere with an effective elastic thickness larger than 20 km is mainly located in out rise of the trenches. The lithosphere over the mid-ocean ridge usually has effective elastic thickness of lower than 5km. The strength of lithosphere over the passive continental margin, such as the southern margin of the Australian continent, is also weak. The effective elastic thickness of lithosphere over the seamount area of the Pacific is about 10 to 20 km.