Abstract: Ma Wei-lian, a kind of Chinese medicinal drugs which is derived from the genus Thalictrum, has been widely used as a substitute for the Chinese traditional drug Huanglian (Rhizoina Goptidis), with antipyretic, antidote and antidysentery effects. After a general survey and taxomonic idendification of the original plants of this drug, 20 plants all belonging to Thalictrum genus were found in the market under the general name "Ma Wei-lian" (of. Tab. 1&2). As a result of ancient herbals study, Thalictrum glandulossimum (Fin. et Gagn.) W. T. Wang et S. H. Wang is supposed to be the genuine one of the drug, chemically it contains besides others an alkaloid hernandazine, which has been proved to possess an antitumor activity. Besides, six species, viz., T. foliolosum, T. foetidum, T flavum, T. ramosum, T. atriplex and T. minus var. hypoleucum were supposed to contain hernandazine by a preliminary TLG comparison. The morphological and histological characters of 20 kinds of "Ma Wei-lian" were described concisely with illustrations, the results showed that all these kinds can be distinguished from each other histologically. By means of TLG and a spectrophotometric method, berberine has been demonstrated to be present in 8 species out of 10 species examined. Those species with higher berberine content were T. glandulissimum var. chaotungense (2.07%),T. glandulossimum (1.485%), T. cultratum (1.465%) and T. foliolosum (1.07%). These results may be of value to the standardization and utilization of these drugs.