Abstract: To clarify the diversity and seasonal variation of butterfly in the Dongjiao coconut forest. An investigation of butterfly diversity was performed by the sample line method in Hainan Dongjiao coconut forest from December 2016 to November 2018. The results indicated that there were 80 species belonging to 54 genera in 9 families were collected. Among them, species richness was highest for the family Nymphalidae (S = 20), followed by Pieridae (S = 13), the lowest were for Amathusiidae and Acraeidae (S = 1). The number of individuals was highest for Pieridae (n = 317), the second was for Lycaenidae (n = 199), the lowest was for Amathusiidae (n = 38). The diversity of the species was highest for Nymphalidae (H(S) = 2.67), followed by Papilionidae (H(S) = 2.10), the lowest were for Amathusiidae and Acraeidae (H(S) = 0). The diversity of the genus was highest for Nymphalidae (H(G) = 2.36), followed by Lycaenidae (H(G) = 1.97), the lowest were for Amathusiidae and Acraeidae (H(G) = 0). The butterfly diversity indexes changes in the seasons. Species richness was highest from June to Aug., which species richness values were 75; the second was from Mar. to May, which values were 72; the lowest was from Dec. to Feb., which values were 36. Diversity index (H(FGS)) was highest from Mar. to May, which values were 9.37; the second was from June to Aug., which values were 9.33; the lowest was from Dec. to Feb., which values were 7.77. Species evenness was highest from Mar. to May, the values were 2.19. Species dominance was the highest from Dec. to Feb., the values were 0.15. The butterfly species abundance curves conformed to the lognormal distribution.