Abstract: The groundwater environmental background value is an important basis for measuring whether the groundwater is polluted, and the groundwater environmental background value is an important yardstick for evaluating the sustainable development level of groundwater in this region. Five groundwater background value unit zonings were divided in this paper based on the hydrogeological and groundwater chemical characteristics of lateral seepage impact zone in the lower reaches of the Yellow River in Henan Province. The groundwater environmental background values and ranges of 8 groundwater chemical indicators in each zoing were calculated using mathematical and statistical methods. The results show that the groundwater background value of Zone Ⅳ in the Yellow River terrace is the lowest, while that of Zone Ⅰ and Zone Ⅱ on the southem bank of the Yellow River is lower. The background values of Zone Ⅴ on the northem bank of the Yellow River and Zone Ⅲ, where the Yellow River turns from east-west to south-west, are higher. The main groundwater types in the study area are HCO₃^--Ca²⁺·Mg²⁺·Na²⁺, HCO₃^--Mg²⁺·Ca²⁺·Na⁺ and HCO₃^--Mg²⁺·Na⁺·Ca²⁺ water. There are high background value areas for Ca²⁺, Mg²⁺, SO₄^2-, Cl^-, TDS and other indicators in the study area. The high background value area of Ca²⁺ and Mg²⁺ may be caused by mineral dissolution and cation exchange, and that of SO₄^2- and Cl^- may be caused by agricultural non-point source pollution. The high background value area of TDS is caused by strong evaporation and concentration in this area. The Gibbs diagram shows that the groundwater in this area is mainly affected by the weathering and dissolution of minerals in the original strata, and is also affected by partial evaporation and concentration. The water quality distribution law of the lateral seepage impact zone in the lower reaches of the Yellow River in Henan Province was identified, and the understanding of the formation and evolution mechanism of groundwater quality in this region was improved. The research results could provide important support for maintaining the sustainable development of regional groundwater.