Abstract: Aiming at the geological environment problems encountered in the coastal zone of Beihai City, Guangxi in recent years, based on the advantages of GIS technology in spatial data management and analysis, an online management and service system of geological environment monitoring data in coastal zone was developed and designed. The online monitoring, integrated management, and dynamic simulation of erosion and deposition data, saline intrusion data, and ecological geochemical data in the coastal zone of Beihai City were realized. The system was applied in the city and has achieved good results. This system provided an effective decision support for the solution of geological environment problems in coastal zones of Beihai City, and offered a reference for other management systems of geological environment data in coastal zone.