In order to revealed the plant community stability on the habitat of giant panda in Qinling Mountains we set two line transects between the altitude of 900-3 071 m in the field,and the standard plots (20 m×25 m) were investigated on transects in Foping and Changqing Nature Reserves.Based on analysis of survey data,community stability of 16 representatives and typical community types were evaluated by subordinate function of fuzzy mathematics.The evaluation index included the regeneration of dominant species,stand qualities,diversity,community complexity,soil fertility and protective degree.The results showed that:(1)according to the analysis of regeneration ability of dominant species in different community tree layer,the quantity of undergrowth seedlings and young trees of Quercus variabilis were the highest and the subordinate function value was largest,showing the regeneration ability was best.However,none of seedlings and young trees grew under the Pinus armandii forest and the subordinate function value was lowest,showing the regeneration ability was worst.(2)According to the analysis of quality of forest land in different communities,the average subordinate function value of growing stock volume and the quality of forest land in mixed forest of Pinus armandii and Pinus tabulaeformis were best.However,the average height and litter depth were the lowest in mixed forest of Pinus tabulaeformis and Quercus aliena var.acuteserrata,the quality of forest land was worse.(3)According to the analysis of forest soil fertility,the membership function of Larix chinensis forest was highest and soil fertility was higher,whereas the subordinate function value of Castanea mollissima and Betula luminifera were lower and the soil fertility was lower too.(4)According to the species diversity of forest land in different communities,the subordinate function value of Tsuga chinensis was the highest which showed a outstanding species diversity,and the subordinate function value of Larix chinensis was lower,showing a lower species diversity.(5)According to the complexity of forest land in different communities,the subordinate function value of three aspects of complexity in Tsuga chinensis was relatively higher which showed high community complexity,whereas the subordinate function value of Larix chinensis was lower and the community complexity was lower too.(6)According to the protective degree of forest land in different communities,the protective degree of Larix chinensis and Abies fargesii were high for they were distributed in core region of protected area,while the protective degree of Castanea mollissima and Betula luminifera were low because of the marginal division of protected area.(7)The subordinate function value showed that the community stability can be arranged as an order of Tsuga chinensis＞Quercus glandulifera var.brevipetiolata＞Populus purdomi＞Pinus armandii＞Quercus aliena var.acuteserrata＞Abies fargesii＞Betula platyphylla=Betula albo-sinensis＞Pinus tabulaeformii+Pinus armandii=Betula albo-sinensis var.septentrionalis＞Pinus tabulaeformis+Quercus aliena var.acuteserrata＞Pinus tabulaeformis＞Larix chinensis＞Quercus variabilis＞Castanea mollissima＞Betula luminifera from high to low.