Abstract:According to the study of isoquinoline alkaloids in Stephania (Menispermaceae) and phytotaxonomy as well as pharmacognosy, the distribution pattern and relativity of alkaloids of this specific category in the genus were approached. The results showed as follows: The main constituents of Stephania are isoquinoline alkaloids. A correlativity between the chemi- cai patterns and plant evolution was found. The structural types and kinds of alkaloid are few in primitive sections and developed greatly in evolution sections. In the subgenus, some alkaloids with special structural types and constituents distributed narrowly in plant, play an important role in the sections of classification.