Abstract: In this papery. explored were the electrophoretic banding patterns (EBP)of peroxidase of 18 wild populations representing all the taxa of Ottelia so far known in China, cytochrome oxidase of seven selected populations and esterase of three chosen ones from the 18 populations, and their systematic significance. The results show that there existed a polymorphism both in EBP of peroxidase of all the taxa studied and in that of cytochrome oxidase of O. alismoides, which means that there is some difference in the genes coding the isoenzymes eoneerned among the populations within a species; all the three isoenzymes detected were of taxonomic importance; O. emersa should be reduced to a synonym of O. cordata, O. acuminata var. lunannsis and var. tonhaiensis be ancelled while var. crispa be kept up, which was in conformity with that based on the morphology. In addition, the relationships between EBP of peroxidase and breeding systems was preliminarily revealed.