Objective: To study on effect of chitosan flocculation sedimentation method on anthraquinones. Method: Taking Rheum palmatum as research object

water extracting liquid of R. palmatum was handled by chitosan sedimentation

with the mass fraction of rhein

emodin

aloe-emodin

chrysophanol

physcion and extract rate as indexes

orthogonal test was used to optimize chitosan flocculation sedimentation by taking the mass concentration and pH of water extracting liquid

the amount of chitosan as factors;And compared with ethanol precipitation method. Result: Optimized chitosan flocculation sedimentation technology was:the mass concentration of water extracting liquid 0.1 g· mL-1 with pH 6

the amount of chitosan 10%.Both chitosan flocculation sedimentation method and ethanol precipitation method could precipitate water extract preferably

but also lead to loss of anthraquinones.The former was better than the latter in reducing extract rate and retaining active ingredients.There was no significant difference between the purified and unpurified liquid by these two kinds of precipitation methods. Conclusion: Effect of anthraquinones by chitosan flocculation sedimentation method was lower than ethanol precipitation method

it could be used in precipitation of Chinese materia medica containing anthraquinones

but it needed more research to decide if this method fitted expandable production.