Abstract: Danjiangkou reservoir is the source of the Middle Route of the South-to-North Water Diversion Project, the geological environment survey of the water source area is very important. During the survey process, the amount of geological environmental data is huge and the degree of comprehensive utilization is low. In order to make more effective use of these data, and meet the needs of multi-source, heterogeneous data management and real-time dynamic update, the paper carried out secondary development on the MapGIS geographic information system platform and the MapGIS IGserver platform, and established the Danjiangkou water source area environmental geological survey data cloud platform based on WebGIS. The establishment of the cloud platform has realized the management and sharing of the geological environment survey results data and field survey data of the water source area. On the basis of studying the characteristics of the geological environment of the water source area, we established a combinable geological environmental quality evaluation system, and realized the cloud evaluation of geological environmental quality. The platform provides geological support for in-depth geological research and analysis and national land planning in the water source area of Danjiangkou reservoir.