【Background】Ambrosia artemisiifolia is a worst worldwide weed and commonly occurs in Nanchang, Jiangxi Province, Southeast China. Ophraella communa and Epiblema strenuana are two important natural enemies of A.artemisiifolia and have significant exploitation and utilization value. However, there are very few studies on the combined control effect of O.communa and E.strenuana on A.artemisiifolia in Nanchang, Jiangxi Province. 【Method】The two natural enemies （O.communa and E.strenuana）were released as 0.7 beetles and 0.4 moths per plant into the areas invaded by A.artemisiifolia in Nanchang, Jiangxi Province, on 25th June 2009. From 4 August to 13 September, the number of O.communa at all the metamorphosis stages, the number of cecidium of E.strenuana, the plant height and mortality of A.artemisiifolia were surveyed every 10 d. 【Result】The two natural enemies increased rapidly in the early stage, but after released for 70 d, the number of the two natural enemies decreased sharply with the mortality of A.artemisiifolia up to 90.14%. After released for 80 d, the mortality of A.artemisiifolia reached to 100%. Furthermore, the plant height of A.artemisiifolia in the releasing area increased very slowly during the measurement period, but was significantly lower than that of the control.【Conclusion and significance】 The joint biological control system with O.communa and E.strenuana has good control effect against A.artemisiifolia and is worth trying out more widely in Jiangxi Province.