Abstract: Betulin was extracted from white birch bark using a modified flooding extraction equipment. The equipment was easy-connected and conveniently-operated. It effectively improved the product purity without the change of yield. The effects of ethanol concentration and extraction time on the yield and purity of betulin was investigated. The optimal conditions were 70% of ethanol concentration, 50 min of extraction time. Under above conditions, the yield of betulin reached (88.39±1.77)% and the product purity was (80.34±0.25)%.