The chemical components of Oenanthe javanica from Guizhou and the hypoglycemic effect of its extracts on the diabetic mice induced by streptozotocin (STZ) was investigated in this paper. The chemical composition type in the wild O. javanica was detected in a single prediction experiment by using various chemical components of natural medicine. The total phenolic acids, flavonoids and sugar of O. javanica were determined by spectrophotometry. Diabetic mice model was established by STZ, and metformin was used as a positive control, the extracts from O. javanica was fed, blood glucose was measured. The results showed that O. javanica contained phenols, flavonoids, alkaloids and other active ingredients, and the total phenolic acids, flavonoids and sugar of O. javanica were found higher than other kinds of compounds. The extract from O. javanica showed a certain hypoglycemic activity, and according to the data, decreasing blood glucose from 27.6 to 17.7. Thus O. javanica from Guizhou contains a variety of natural drug chemical composition, showing a certain hypoglycemic effect, and it was valuable to research and explore it.