Abstract: The plant functional group (PFG) is one of the important fields in vegetation science research, and is a basis for exploring the structure and function of plant community and analyzing the succession and species diversity, functional diversity and phylogenetic diversity of plant community; moreover, it could provide the theoretical basis for vegetation restoration. Based on the dataset investigated from the field, 61 plots and 207 species were recorded in Yunding Nature Reserve, Shanxi of northern China, among which 47 herb species were regarded as dominant species, and the PFG of 47 herb dominant species was studied by Fisher's exact test and Spearman's rank correlation analysis with clustering analysis (median method), respectively in order to achieve the division of the PFG in this mountain. The results indicated that:1)There were 46 species-pairs being highly positive association (P < 0.01) and 5 species-pairs being highly negative association (P < 0.01), 24 species-pairs being positive association (P < 0.05) and 10 species-pairs being highly negative association (P < 0.05) and 46 species-pairs being highly positive association (P < 0.01), 996 species-pairs being not significant association (P>0.05) by Fisher's exact test. 2)There were 72 species-pairs being highly positive correlation (P < 0.01) and 9 species-pairs being highly negative correlation (P < 0.01), 33 species-pairs being positive correlation (P < 0.05) and 8 species-pairs being highly negative correlation (P < 0.05), 959 species-pairs being not significant correlation (P>0.05) by Spearman's rank correlation analysis. 3)The species-pairs being not significant association (996) accounted for 92.14% in the total species-pairs by Fisher's exact test, and the species-pairs being not significant correlation (P>0.05) (959) accounted for 88.71% in the total by Spearman's rank correlation analysis. It suggested that the niche among those species had obvious differentiation and the sensitivity of the latter was more than the former. 4) Based on the results of species relationship by Fisher and Spearman combining the clustering results, the PFG was divided into 5 groups, including PFG in the subalpine area, PFG in the lower elevation areas, PFG in the herb layers of the forests and shrubs, PFG in the herb layer of the forests and the PFG in the herb communities of the middle elevation areas. Based on the above results, it is suggested that the PFG is closely related with the community type, habitat, life type and niche.