Abstract: By using the Gynostemma Pentaphyllum Makino as material,the experiment was carried out in order to study theapplication effect on the separation of saponin of Gynostemma Pentaphyllum Makino by the membrane technology of micro-filtration to clarify,ultra-filtration to get rid of big molecule substance,nanofiltration to separate or concentrate.The resultsshowed that 0.2μm micro-filtration membrane could clarify the extracted liquid efficiently at 40℃ when added the same weightdialysis water as the extracted material when the weight of filtrated liquid reached 80% the weight of extracted liquid;The ultra-filtration membrane whose holding up molecule was 10000Da could get rid of big molecule substance ;The saponin products ofGynostemma Pentaphyllum Makino whose content of saponin was higer than 42% could be obtained by choosing the 2500Dor 3500D nanofiltration membrane,furthermore,3500D nanofiltration membrane had a little higher rate of preparation than thatof 2500D nanofiltration membrane,but the purity of saponin in the dried products had the reverse result;At last,concentratingthe saponin of Gynostemma Pentaphyllum Makino by choosing the 500D nanofiltration membrane on the condition of 32℃and 1.8MPa not only could have higher concentration rate ,but also could enhance the purity of products.

Key words: saponin of gynostemma pentaphyllum makino, micro-filtration, ultra-filtration, nanofiltration