Abstract: The authors carried out the 1∶100 000 geological survey of coastal wetland and evaluation of ecological environment for the first time in western South China, based on remote sensing, single beam measurement, geological sampling, seawater sampling, drilling, groundwater collection and monitoring. The types and distribution of coastal wetland, topography of coastal waters, sedimentary environmental quality, seawater environmental quality, evolution of ecological geology, and chemical elements of groundwater were comprehensively analyzed and studied. The authors ascertained the types, distribution, ecological environment situation and its main influencing factors of coastal wetland in the study area. The eco-geological environmental quality of the wetland was comprehensively evaluated. The authors built the technical method system of geological survey and the comprehensive evaluation system of eco-geological environment in coastal wetland of South China, and put forward some suggestions for the protection and restoration of coastal wetland. The achievements can provide a demonstration for the follow-up survey of coastal wetland in South China.