Abstract: Using total alkaloids as the guide, influencing factors of extraction yields of alkaloids from Cynanchum komarovii including solvent concentration (using hydrochloric acid and ethanol as extract solvent) and extracting method (using water as extract solvent) were studied. And using light absorbing range as the guide, the influencing factors of purification of the crude extract such as kind of flocculant, dosage of flocculant, temperature of flocculating system, pH value of flocculating system were studied based on single factor test. The results showed that the obtainment of total alkaloids were highest when extract with 60% ethanol, and the optimal flocculating conditions were: under 50℃, pH value were 4~5, adding the NO.1 flocculant as 20%(v/v) of crude extract.