18 groups of Shuangcui karst water samples were collected in September, 2013. The hydrochemical characteristics of the samples was analyzed, and R factor analysis method was applied to investigate the dominant factor that impacted the chemical composition in this Karst area. According to the results, under the alkalescent geochemical background, Mg2+, K+ and F- in the Karst water was mainly influenced by ion isomorphism in aeration zone from groundwater. Cl-, Na+, NO3- and SO42- were related to man-made pollution while HCO3-, Ca2+ and PH values were impacted by carbon sink. 87.103% of the formation cause of hydrochemical characteristics of the Karst water in Shuangcui water system could be explained by these 3 factors mention aboved.