Total six compounds were isolated from the methanolic extract of Polygonum flaccidum and structural elucidation of the yielded compounds using intensive studies of their NMR spectrometry confirmed them as 1, 7, 8-trimethoxy-2, 3, 5-trihydroxy anthraquinone (1), 1, 2, 3, 6, 7, 8-hexamethoxy anthraquinone (2) 1, 7, 8-trimethoxy-2, 3, 5, 6-tetrahydroxy anthraquinone (3), β-sitosterol (4), decanoic acid (5) and 1-tetradecanol (6). Literature survey revealed that compound (1), (2), (3) is the new compound from natural products. The isolated compounds 5, 6 are the first time report from this plant. Therefore, the plant is a good candidate for further studies to isolate the bioactive principles to identify leads for drug development.