With the rise in sea level,the extreme value and return period of the annual highest water level in coast areas are changed,which insert a significant influence on the determination of the top elevation of coastal engineering.Taking Wusong as a case,we research the top elevation of docks,calculate the return period by the pure experience curve method,and analyze changes of the dock’s top elevation of under the scenario claimed by IPCC AR5.The results show that the sea level rise affects obviously on the determination of dock’s top elevation,especially when the top elevation is not that high.