目的：制取２０（Ｓ）原人参二醇组皂苷并将其转化制备抗癌活性单体２０（Ｓ）人参皂苷Ｒｈ２。方法：以国产西洋参茎叶总皂苷为原料，通过萃取法制备２０（Ｓ）原人参二醇组皂苷；将２０（Ｓ）原人参二醇组皂苷碱催化水解后，经柱层析分离纯化制备２０（Ｓ）人参皂苷Ｒｈ２。结果：２０（Ｓ）原人参二醇组皂苷收率为４１．５％，其转化成２０（Ｓ）人参皂苷Ｒｈ２的转化率为９．６４％。结论：制取方法简便，收率较高。 OBJECTIVE: To prepare 20(S)-protopanaxadiol saponins and transform them into anticancer active monomers 20(S)-ginsenoside-Rh2. Methods: The saponins of 20(S)protopanaxadiol were prepared by extraction with the total saponins of stems and leaves of Panax quinquefolius made in China. The basic hydrolysis of 20(S)protopanaxadiol saponins was followed by column chromatography. The purified 20(S)-ginsenoside-Rh2 was prepared. Results: The yield of 20(S)-protopanaxadiol saponin was 41.5%, and the conversion rate of 20(S)-ginsenoside-Rh2 was 9.64%. Conclusion: The preparation method is simple and the yield is high.