In this study, the overall editing criteria for altimetric data are considered and the geophysical correction models is improved. The datum for various altimetric data is also unified and the method of a full-combined crossover adjustment for different altimetric tracks is used to improve the radial orbits of Geosat, ERS-1 and ERS-2 data. In addition, the method for determining mean sea surface (MSS) by using multi-altimetric data is developed. The data used to compute WHU2000 MSS include 7-year Topex/Poseidon data (cycles 11-249), 2-year Geosat ERM data (cycles 1-44), 5- year ERS2 data (cycles 1-52) and all ERS-1 168-day data. The WHU2000 MSS is determined with a grid resolution of 2′× 2′ within the ± 82° latitude and its precision is better than 0.05 m. Comparing WHU 2000MSS with 3.75′ 3.75 CLS_SHOM98.2 MSS, 3′×3′ GFZ MSS95A and 3.75′×3.75′ OSU MSS95, as external checks, the corresponding standard deviation (STD) of their differences is 0.090 m, 0.211 m and 0.079 m respectively.