Our system uses high as normal height datum, elevation into the Yellow Sea in 1956 and the Department of National Height Datum 1985
1.1956 According to the Department of the Yellow Sea mean sea level elevation data to determine the Yellow Sea tide between 1956 and June 1950 Qingdao tide station as a reference elevation.
2.1985 National Height Datum Qingdao tide station from 1952 to tidal observations between 1979 and calculated on the basis of 27 years.
3. The results of the overwhelming majority are using 1985 National Height Datum. As China's legal system, the normal high, after conversion to 2000 in 80 coordinate system coordinates, ground elevation is still using 1985 National Height Datum. ( Https://www.zhihu.com/search?type=content&q=WGS84 ).