中文摘要：

本文利用最新全球重力场模型EGM2008和GPS水准数据计算了我国1956黄海高程基准面和香港主要高程基准间的垂直偏差和重力位差．计算结果表明，这两个基准面问的重力位差为8．065±0．343m^2s^-2，即我国1956黄海高程基准面平均高于香港主要高程基准面82．4±3．5cm．同其它重力场模型及局部重力场模型计算的结果和实测值的比较表明，EGM2008模型的结果更加精确可靠．这将为我国在未来的海岛礁测绘中实现跨海高程基准的传递提供一种经济可行的方案．

英文摘要：

The height of a point for most surveying applications is referred to a ＂local height datum＂ or ＂local geoid＂ which is an equipotential surface defined by an accessible point called ＂origin point＂. There are height datum bias between different local height datums. Technological developments and the increasing need of cultural, scientific and industrial exchanges of data, make necessary the availability of geospatial information in the form of unified national, regional and global geospatial information systems. This goal requires the unification of the height datum all over the world. The key issue of height datum unification is to determine the potential differences among different height datums. By using the newest global Earth＇s gravity field models EGM2008 and high precision GPS/levelling data, the height difference and geo-potential difference between 1956 yellow sea height datum of China and Hong Kong Principal Datum（HKPD） are calculated in this paper. The geo-potential difference is 8. 065±0. 343 m^2s^-2. Namely, the 1956 yellow sea height surface of China is averagely 82. 4 ± 3. 5 cm higher than the surface of HKPD. In comparison to other global and local earth＇ s gravity field models and the measured value, the results obtained by EGM2008 are more accuracy and consistent with the ground leveling result to a few centimeters.