Abstract: In order to investigate the predatory potential of the predatory gall midge Aphidoletes aphidimyza (Rondani) on different instar stages of tobacco aphid Myzus persicae (Sulzer),we studied the functional response of second and third instar larvae of A. aphidimyza and intraspecific interference effects of third instar larvae of the predatory midge. Our results showed that when fed with tobacco aphids at different instar stages, the functional response of second and third instar larvae of the midge fit the model type II. Second instar larvae of the predatory midge have the shortest handing time (2.0525 h) and the highest theoretical predation amount (11.69) when fed with first or second instar tobacco aphids. Third instar larvae of the predatory midge have higher potential predation compared to second larvae and better suppression effect on older instar tobacco aphids. Daily predation of third instar larvae on different instars tobacco aphids were obviously increased with increased density of predatory midge, but the average predation rate was the opposite. Intraspecific interference effects of third instar larvae were varied when fed with different instars tobacco aphid M. persicae. The interference degree when feed on tobacco aphid M. persicae was first to second instar (0.76) > fourth instar (0.64) > third instar (0.57). In summary, the predatory midge A. aphidimyza has a high potential with suppression control ability that can be used to control tobacco aphid M. persicae.