From 2016 to 2018, the line transect method was employed to survey butterfly species in Jiuwan Mountain National Nature Reserve, analyzing the composition and diversity characteristics of butterfly communities. Results revealed a total of 6965 butterfly individuals, belonging to 169 species, 96 genera, and 5 families. Among these, the family Nymphalidae had the highest number of genera (39), species (85), and individuals (3544); the family Pieridae had the fewest species (15), while Hesperiidae had the fewest individuals (416). The individual counts of 126 butterfly species accounted for less than 1% of the total, classifying them as rare taxa. The evergreen broad-leaved forest zone exhibited the highest diversity index, while the shrubland and large lake zone showed the highest similarity coefficient (0.56). With increasing elevation, butterfly species, dominance index, and richness index demonstrated a pattern of initial decrease followed by an increase, while diversity and evenness indices showed an initial increase followed by a decrease. Although Jiuwan Mountain National Nature Reserve supports rich butterfly diversity, the high proportion of rare taxa and the apparent declining trend in butterfly abundance suggest that butterfly community diversity in this region faces threats. Therefore, strengthening monitoring and conservation efforts for butterfly resources, particularly for rare taxa, is recommended to maintain biodiversity in this area.