Abstract: The Songnen Plain in Jilin Province is a significant region of endemic fluorosis. With study on the distribution of disease areas, the source, migration and enrichment of fluorine in groundwater, this paper discusses the hydrogeological process of groundwater from runoff-catchment to enrichment and formation of high-F water. Based on the hydrogeological characteristics and years' practices of water improvement, the measures of drinking water change are made for the region.