Far from the mainland,far-sea islands and reefs often lack basic surveying and mapping data,thus trans-sea elevation transfering is a difficult problem in the construction of offshore islands and reefs.Aiming at this problem,combining with an engineering case abroad,the theodolite dip method,GPS leveling method and synchronous mean sea level method are discussed,and the principles,calculation methods and applicable conditions of different methods are analyzed.The results show that the synchronous mean sea level method is simple,accurate and reliable for transfering trans-sea elevation of far-sea islands and reefs with the same tidal properties,and can be used as the preferred method for similar projects.