Based on the datasets of 149 plots from the wetland herb communities in Zhuozhang River watershed, Shanxi, the relationships of 27 dominant species were analyzed by Spearman rank correlation coefficient test. The results showed among 351 pairspecies, the pairspecies of negative association (242 pairspecies) were dominant, and the ratio of positive to negative association was 3:7. The proportion of speciespairs having a significant or highly significant correlation was 16.8%. According to the association of dominant species and the adaptability of species to habitats (mainly moisture conditions), the dominant species were divided into four plant functional groups (PFGs): mesophyte, mesohydrophyte, hygrophyte and hydrophilous. The PFGs along the moisture gradient were distributed in the top of flooding plain, the lower of flooding plain, the seasonal watering area of flooding plain, and the river and marsh of Zhuozhang River, respectively.