Background: Fissistigma polyanthum is a liane belonging to the Annonaceae family and it is one of the most important crude drugs in traditional Chinese medicine. Objective: The objective was to describe the structural elucidation and the free-radical-scavenging activities of the isolated compounds from Fissistigma polyanthum. Material and Methods: The chemical constituents were isolated and purified by normal, reverse column chromatography and HPLC. Their structures were identified by spectroscopic methods ( 1 H NMR and 13 C NMR) and by comparison with literature values, and the free-radical-scavenging activities of these two compounds were also evaluated through three in vitro model systems (DPPH, trolox equivalent antioxidant capacity (TEAC) and Co (II) EDTA-induced luminol chemiluminescence by flow injection). Results: Two known compounds, named kanakugiol (1) and teutenone A (2), were isolated from the stem of Fissistigma polyanthum for the first time, and compound 1 exhibited moderate free-radical-scavenging activity. Conclusion: Fissistigma polyanthum, which has traditionally been used as an important Chinese medicine, showed a certain free-radical-scavenging activity.