The global sea level trend is generally adopted to calculate wharf deck elevation in port engineering at home and abroad,and the local and temporal characteristics of sea level variations are neglected.We discuss the mechanism and characteristics of sea level,and point that sea level variations include seasonal variation,inter-annual variation,decadal variation and long-term trend.The influences of local and temporal characteristics of sea level should not be neglected in the determination of wharf elevation.The results show that in order to determine the wharf elevation,besides considering sea level trend,the necessary seasonal,inter-annual and decadal corrections should be carried out on the basis of the time length of water level data.