Abstract: Land-sea coordination is an important tendency in our coastal geological work, but the work was usually separately carried out for land area and sea area in the past, and there is no uniform understanding about how to achieve land-sea coordination. As one of the pioneers that carried out coastal geological work in China, Shanghai has conducted some beneficial attempts and accumulated some experience in land-sea coordination. Based on the practical experience, and combined with current status of coastal geological work at home and abroad, the authors discussed the methodology of land-sea coordination in coastal geological work and proposed that land-sea coordination in coastal geological work should include two essential contents. And they are the organic integration of land and sea achievements and the land-sea linkage through the intermediary of water bodies. To achieve the land-sea coordination, the followings need to be paid more attention to in coastal geological work. In fieldwork deployment, the intermediary effect of land rivers and sea islands should be utilized, and geological achievements mapping should concentrate on the region instead of local areas. In geological environment monitoring, the seawall and shoreline as the link are used to synchronously monitor the land and sea. In achievements mapping, to organically integrate land and sea achievements, the key is to unifyd land-sea data standards, and the classification of data level should be simplified properly with data science information preservation.