Introduction to China’s Level Zero Point: The “People’s Republic of China Level Zero Point” in Yinhai World, Donghai Middle Road, Qingdao City, is the only Level Zero Point in China. The horizontal zero point is the starting surface for calculating the elevation of ground points. The average sea levels measured by tide gauge stations at different locations are different. To unify the national elevation system, a mean sea level is selected as the elevation datum. China stipulates that the 1956 average sea level of the Yellow Sea obtained from the Qingdao Tide Gauge Station is the "national unified elevation datum", and the elevations calculated from other different elevation datums are normalized to the unified elevation datum.