Through the textual criticism of datum level and basic benchmarks at the Suixian station, a conclusion was made that the preliminary observation at the basic benchmarks of TONG BM3 and SUI BM1 established at early times does not meet the relevant requirement. The three repletion measurements carried out in 1985, 1986 and 2000 exceeded the limitation. However, it is right to process the measurements according to the unchanged datum level relationship. The average of two measurements in 2005 was considered to be the height of the new benchmark, and the difference between national datum level and stationary datum level (DNDSD) was estimated with old benchmark of SUI BM1, which can assure the consistence of hydrologic level data before and after the section up movement?of the hydrologic station.