Abstract: In order to promote the application of Xanthium sibiricumstem and leaf extract in the development of biopesticides,the aim of this study effects of extracts from Xanthium sibiricum on toxicity activity of Aphis glycines the ultrasonic extraction method was used to extract stem and leaf of Xanthium sibiricumfrom May to September.The toxicity activity and potted control effect of extracts from different periods Xanthium sibiricum on Aphis glycines were studied.The results showed that the extraction rate of Xanthium sibiricum stem and leaf extracts from May to September was between 13.98%and 23.50%,the highest extraction rate was on July 27 th,the second one was on August 10 th.The toxicity activity was between 56.12% and 84.92%,the highest was on August 10 th.The best potted control effect was on August 10 th which was 78.15%.Considering the extraction rate,toxicity activity and the control effect of Aphis glycines,it could be concluded that the best date of Xanthium sibiricum extracts was August 10 th.Although the concentration of 40 mg·mL-1 was less effective than that of Pymetrozine in the field control of Aphis glycines,the 7 days after treatment control effect reached 72.54%,which was suitable for the field biological control of Aphis glycines.