[Objective]To study the anti-tumor active ingredients of Betula albo-sinensis Burk.bark.[Method]The compounds were isolated and purified by bioassay-guided procedure using various chromatographic methods and the structures were identified by modern spectroscopic technology.[Result]Five pentacyclic triterpenoids were obtained from the active substances of chloroform extract and identified as lup-20(29)-en-28-ol-3β-yl caffeate(Ⅰ),betulin(Ⅱ),lupeol(Ⅲ),betulinic acid(Ⅳ) and betulonic acid(Ⅴ).All the compounds showed cytotoxic activities on Bel-7402,B16 and A549 cell lines.[Conclusion]All the compounds obtained from this study were isolated from Betula albo-sinensis Burk.firstly. [Objective] To study the anti-tumor active ingredients of Betula albo-sinensis Burk. Bark. [Method] The compounds were isolated and purified by bioassay-guided procedure using various chromatographic methods and the structures were identified by modern spectroscopic technology. [Result ] Five pentacyclic triterpenoids were obtained from the active substances of chloroform extract and identified as lup-20 (29) -en-28-ol-3β-yl caffeate (I), betulin (II), lupeol (III), betulinic acid IV) and betulonic acid (V). All the compounds showed cytotoxic activities on Bel-7402, B16 and A549 cell lines. [Conclusion] All the compounds were obtained from this study were isolated from Betula albo-sinensis Burk.firstly.