A new compound was isolated from Helichrysum arenarium(L.) Moench and Phyllostachys nigra vear.hnouis(Bean) Stepf ex Rendle respectively at the same time by the column chromatography on silica gel,Sephadex LH-20 and elucidated as 6,7-dimethoxy-4-hydroxy-1-naphthoic acid by the physico-chemcial characters and spectroscopic methods(UV,IR,1D,2D-NMR,ESI-MS).