The evaluation of groundwater quality serves as a scientific basis for the exploitation and protection of groundwater resources. The indicators of traditional water quality assessment models are random, fuzzy and uncertain. In view of this, a set pair analysis model based on entropy method is established and applied to the groundwater quality assessment for Hamatong drainage basin. According to data of 86 monitoring points, six indicators, including NH₄⁺, NO₂^-, Fe²⁺,Mn²⁺, Zn²⁺, and COD_Mn are selected and given weight by using entropy weight method. The assessment result is compared with that of modified Nemerow index method. The results implies that the groundwater quality of Hamatong drainage basin is below average, with Ⅳ and Ⅴ levels accounting for a large water area, while Ⅱ and Ⅲ levels occupying a small area. The assessment result is consistent with that of the modified Nemerow index method, both comforting well with reality. The set pair analysis model based on entropy weight is proved rational and reliable.