Abstract: Based on the investigation of the vegetation and collection of samples,the flora composition of Dashu Mountain in terms of families,genera,and species were analyzed and the R/T rate were compared with floras in similar latitude sites.A total of 508 plant species,belonging to 315 genera and 120 families were recorded,among which Pteridophyte had 10 families,13 genera and 14 species;gymnosperms had 7 families,19 genera and 47 species;and angiosoerms had 103 families,283 genera and 447 species.The dominants of the forest community was mainly composed of Fagaceae,Pinaceae,Ulmaceae,Aceaceae,Tiliaceae,and Leguminosae,etc.The analysis of floristic geographical elements indicated that the 226 genera fell into 14 types.Athough the temperate zone component held a certain proportion,tropical species were rich,with temperate affinities elements accounting for 23.81% and the tropic affinities accounting for 18.52%,which presents an especially transitional nature.The number of species endemic to China was few.The deciduous broad-leaved forest in temperate zone component was still a relatively stable forest cover of the area.According to the comparison analysis in terms of R/T rate,the tropic characteristics of Mt.Dashu flora were higher than those of the Yaoluoping Nature Reserve,Anhui and Mt.Huangcangyu,Anhui,lower than those of Mt.Mufu,Nanjing and Mt.Langya,Chuzhou,and similar to those of Mt.Zijin,Nanjing and Mt.Niushou,Nanjing in terms of genera.