Abstract: Compared with the center of Sichuan Basin, the red beds distributed in the southern margin of it are characterized by many geomorphological types, large topographic slopes, well-developed structures and steep dipping, and there are few reports on the development regularity of the saline water in the red beds.Through investigation, hydrogeological drilling, sampling analysis and testing, it is found that the development of salt water is mainly controlled by lithology and groundwater circulation.Soluble salt in red sandstone and mudstone is the material basis for the development of salt water.Salt water is more likely to develop in mudstone-bearing strata.Groundwater type, slope structure, depth and fault mainly affect the cycling conditions of groundwater.Fresh water is strongly developed in cycling alternation, while salt water is developed in slow cycling alternation.Salt water with complex composition in the deep part of the fault zone will well up due to exploitation of shallow groundwater, resulting in salinization of shallow groundwater.The study result has reference significance for avoiding saline water layer in the process of water exploration in red beds in the southern margin of Sichuan Basin.