Riparian areas are unique although often small component of the overall watershed landscape. The structure of riparian forests along Erdaobai River on the north slope of Changhai Mountain were investi- gated by using field data collected from eight sampling transects perpen- dicular to the Erdaobai River channel. Two kinds of species-area satura- tion curves were used to examine the relationship between species num- ber and minimum sampling area. The results showed that riparian gym- nosperms accounted for a high proportion of all gymnosperms in the Changbai Mountain Nature Reserve while riparian ferns and angiosperms accounted for a relatively low proportion. The average minimum sam- pling areas of riparian forest that included 60％, 80％, and 90％ of the community species pool were about 85, 185, and 328 m, correspondingly.