[Aim] The common ragweed Ambrosia artemisiifolia is an important invasive weed, which seriously endangers agricultural production and human health. Ophraella communa (Coleoptera:Chrysomelidae) and Epiblema strenuana (Lepidoptera:Tortricidae) are two specific natural enemies of this plant. Study on the control effect of these two natural enemies and their population dynamics in Yongzhou will provide information towards effective utilization of these two natural enemies.[Method] O. communa and E. strenuana were artificially released in a large area of common ragweed in Jiangyong County, Yongzhou City, Hunan Province. The population dynamics of these two natural enemies and their control efficiency on A. artemisiifolia in the released and expanded fields, and their wintering in the expanded fields were investigated.[Result] All instars of O. communa and galls of E. strenuana were found in the released field one month after release. Overall, the population density of each instar O. communa increased first and then decreased, while the population density of E. strenuana was always low and decreased with time. O. communa and galls of E. strenuana were found on common ragweed 10 km from the edge of the released field after two months. Populations of these two natural enemies were successfully established and overwintered safely. In the release field, the height of common ragweed hardly increased, and the leaves were eventually eaten and almost all plants died. In the newly colonised fields, plant height increased slightly, and nearly 75% of the leaves were eaten.[Conclusion] O. communa and E. strenuana successfully established in Yongzhou City and succesfully overwintered, then spread autonomously, and showed strong promise to control common ragweed.