[Objectives]The study aimed at examining how drought stress on wheat plants influenced developmental performances of the caterpillar Mythimna separata feeding on the plants and its larval parasitoid Meteorus pulchricornis. [Methods]Drought treatments at varying levels of PEG6000 in water were applied to potted wheat seedlings,on which M. separata neonate larvae fed to complete the development. The 3rd instar caterpillar was provided as the host to M. pulchricornis for parasitism. The host and its parasitoid developmental parameters were estimated. [Results]The drought treatment decreased M. separata larval duration,survival,pupa body fresh weight,and adult body dry weight,compared to the controls. Compared to the control,the high level drought treatment(0.20 g·mL~(-1) PEG6000)extended larval development time by 4.60%,reduced larval survival by 21.00%,reduced pupa weight by 11.76%,and decreased adult body weight by 33.33%. The low level drought(0.05 g·mL~(-1) PEG6000)extended M. pulchricornis egg-larval duration to 10.15 d on average,as compared to the control(9.55 d),while the high level was not different from the control. The high level of drought decreased parasitoid pupa body fresh weight by 0.31 mg and shortened female adult hind tibia length by ca. 0.04 mm,as compared to the control,while the low level treatment was not different from the control. [Conclusions]The results of this study suggest that drought stress on wheat crop plants can impair the development of M. separata feeding on the plant and have an indirect,adverse effect on the development of the parasitoid M. pulchricornis attacking the larvae.