The species Euonymus duanensis (Celastraceae), a small shrub, is newly described and illustrated from karst areas of Guangxi Autonomous Region, China. This species is similar to Euonymus dielsianus but is readily distinguished by its smaller leaves, obovate or elliptic-obovate, 2-2.5 × 5-6 cm (vs. 4.5-6 × 9-15 cm), blade margin crenulate, serrulate to serrate (vs. margin proximal 1/5-2/5 entire, distal 3/5-4/5 crenulate, serrulate to serrate, sometimes ciliate), reddish flowers and petals (vs. flowers and petals green, light yellow, or greenish yellow), short petiole, milk white seeds (vs. dark brown), and aril bright red partial covering seed (vs. aril bright red covering seed wholly). Phylogenetic study also revealed apparent phylogenetic position of the new species among Euonymus species, and the relationships between related species have also been discussed.