Abstract: The coastline is a key element of basic geographic information for land-sea coordination, and its scientific and accurate determination is of great significance for coastal zone management. This study systematically reviews the definition, classification, and surveying methods of the coastline, compares and analyzes the results of traditional trace coastline measurement and coastline measurement based on the tidal model.We further discuss the differences and problems in the definition, classification, and determination of the coastline. Based on the problems in the coastline measurement and the progress in theory and practice, we propose that one can define the coastline as the boundary line between the sea and land formed by the intersection of the multi-year average high tide surface and the coast,and suggest that one can use a joint tidal model and DEM determination method for determining the coastline based on surveying and mapping. The definition and surveying methods of coastline based on surveying and mapping proposed in this study can provide the unified, accurate and objective coastlines.