Coumarinlignan (1), possessing a unique coumarin-containing lignan skeleton, was isolated from the stems of Kadsura heteroclita. Its structure and absolute configuration were determined by spectroscopic techniques, especially 2D NMR and X-ray crystallographic data analyses. The proposed biosynthetic pathway is discussed. This new compound showed good anti-HBV activity against HBeAg and HBsAg, and moderate anti-fibrotic and neuroprotective activities.