Abstract: Based on the identification of about 1000 specimens of butterflies collected in Yun7 tai low mountain, the diversity and fauna of butterflies of Yuntai low mountain are concluded: 76 species of butterflies are classified in 7 families and 54 genus. These are Papilionidae 5 genus and 11species, Parnassiidae 1genus and 1species, Pieridae 5 genus and 6 species, Satyridae 7 genus and 12 species, Nymphalidae 15 genus and 18 species, Lycaenidae 10 genus and 15 species, Hesperiidae 11genus and 13 species. The result of a series analysis shows that the percentages of Oriental species, Palearctic species and widely distributive species are 35.53%, 18.42%, 46.05%, respectively. According to the comparison of the similarity, the fauna composition of butterflies is most kindred between Yuntai low mountain and Ningzhen low mountain in Jiangsu Province. Because of the influence from marine climate, the fauna composition of butterflies in Yuntai low mountain is very different from Xiangshan low mountain, so we can see that regional environment impact on the fauna composition most.