OBJECTIVE:To investigate the effect of polyamide on the separation on phenolic acids components by nanofiltra-tion process. METHODS:Phenolic acids components were selected as targets,extracted from the Salvia miltiorrhiza,Lonicera ja-ponica or intermediate preparations (tea polyphenols) with water,and filtered with membranes with different pore sizes. The con-tent changes of components were analyzed by HPLC. RESULTS:Danshensu,protocatechuic aldehyde and caffeic acid could better transmit nanofiltration membranes with 3 different pore sizes;with the decrease of pore size,the rejection rates of neochlorogenic acid,chlorogenic acid,rosmarinci acid,ECG and EGCG grew in different levels. But salvianolic acid B was almost retained by the membrane with low molecular weight except 600-800 Da. CONCLUSIONS:Molecular weight importantly influenced nanofiltra-tion separation on phenolic acid components;nanofiltration has a good prospect in enrichment of phenolic acids components.