Abstract: In recent years,Quanzhou City has placed increasing emphasis on the groundwater quality in its economically developed eastern plain region.Based on an evaluation of the hydrochemical characteristics and water-rock interactions in the study area,principal component analysis (PCA) was employed to identify potential pollution sources.The absolute principal component score-multiple linear regression (APCS-MLR) receptor model was further utilized to quantify the contribution of each factor to groundwater quality in the basin.The results indicate:The predominant hydrochemical type of groundwater in the eastern plain of Quanzhou is HCO₃^-·Cl^--Na⁺+K⁺·Ca²⁺,with a trend toward Cl^--Na⁺+K⁺.Rock weathering is the primary factor influencing the hydrochemical composition in the study area,with silicate weathering being the main control on groundwater hydrochemical characteristics.In addition to rock weathering,groundwater is also affected by domestic sewage and agricultural activities.Five principal components affecting water quality were extracted using PCA:seawater intrusion factor (27.78%),chemical manufacturing mixed factor (19.61%),water-rock interaction and building material industry mixed source factor (12.44%),agricultural activities and food processing mixed pollution factor (9.49%),and domestic sewage and natural geological environment mixed factor (6.98%),with a cumulative variance contribution rate of 76.31%.The APCS-MLR model quantified the contributions of these five factors to regional groundwater quality,with average contribution rates of 19.40%,16.26%,7.47%,4.37%,and 22.32%,respectively,while unidentified sources accounted for 30.18% on average.The study reveals that seawater intrusion,chemical manufacturing mixed factors,and domestic sewage combined with natural geological environment factors are the primary contributors to the decline of groundwater quality in the region.