Abstract: The chemical constituents and antioxidant activity of the fruiting bodies of Lenzites betulinus were studied. Six malsterols compounds steroids were isolated from the methanol extract of L. betulinus by various column chromatography techniques. The structures of the isolated compounds were identified by modern spectroscopic analysis techniques, which are(22E, 24R)−ergosta−7, 22−dien−3β−ol(1), 5α, 8α−epidioxy−(22E, 24R)−ergosta−6, 22−dien−3β−ol(2), ergosta−7, 22−diene−6β−methanoxy−3β, 5α−diol(3), (22E, 24R)−ergosta−7, 22−dien−3β, 5α, 6β−triol(4), 3β, 5α−dihydroxy−(22E, 24R)− ergosta−7, 22−dien−6−one(5), 3β, 5α, 9α−trihydroxyergosta−7, 22−dien−6−one(6). Among them, compounds 3, 5 and 6 were first report from L. betulinus. The antioxidant activity of the above compounds was evaluated by using the DPPH free radical scavenging model. The results showed that the scavenging rate of DPPH free radicals was less than 10%, when the concentration of the compounds was 400 µg/mL. Although the antioxidant activity couldn't be comprehensively evaluated, it still had certain guiding significance. In this study, the chemical constituents of L. betulinus were studied to provide a reference for further development and utilization of its resources.