As an important part of the northern sand control belt and an ecological protection area in the lower reaches of Shiyang River, the northern desert area of Minqin Oasis has a low research degree in groundwater hydrochemistry. On the basis of field investigation, exploration and sampling test, the hydrochemical characteristics and cause of groundwater in the northern desert area of Minqin Oasis were analyzed by using the methods of mathematical statistics, Piper trigram, ion correlation analysis, Gibbs diagram and ion proportion coefficient. The results show that the total dissolved solids and hardness of groundwater in the study area are relatively high, and the main hydrochemical type is Cl-·SO2-4－Na+. The groundwater quality can generally meet the needs of planting xerophyte and salt- tolerant vegetation in the ecological barrier area. The hydrochemical evolution of groundwater is dominated by evaporation concentration, accompanied by weathering dissolution and cation exchange. The excessive high nitrate nitrogen in groundwater is related to livestock manure pollution, and the formation of high fluoride water is affected by the original geological environment background. The results not only further improve the research level of groundwater hydrochemistry in the area, but also provide scientific basis for Minqin Oasis protection, the construction of the northern sand prevention belts and the ecological protection and control area in the lower reaches of Shiyang River.