Abstract: According to IR, UV, MS and NMR spectra of the compounds isolated from the fresh stem of Dendrobium loddigesii Rolfe (a Chinese medicine), 3 constituents were identified. They are shihunidine, shihunine and dendrophenol (4, 4 '---dihydroxy -3, 3', 5- trimethoxybibenzyl). Chemical reactions showed that shihunidine was derived from shihunine during isolation. Shihunidine and shihunine were shown to be inhibitors of Na⁺, K⁺-ATPase of the rat kindney.