Climate change is projected to increase temperature and cause greater variability in precipitation, leading to more frequent and heavy drought. The aim of this study is to examine the effects of drought stress in wheat seedlings on the food consumption and utilization efficiency of leaf-chewing Mythimna seperata caterpillars. Drought treatments were applied on potted wheat seedlings at 4 levels of 0 g·mL~(-1)(control), 0.05 g·mL~(-1)(low), 0.1 g·mL~(-1) (medium) and 0.2 g·mL~(-1) (high) of Polyethylene Glycol (PEG) 6000 in water. The wheat plants from different treatments were used to feed M.seperata larvae, then the food consumption and utilization efficiency of M.seperata larvae were calculated, The analysis of covariance (ANCOVA) and classical food utilization indices were used to evaluate the effects. The ANCOVA results showed that drought stress treatment in wheat decreased the food consumption amount and body weight gain of larvae, leading to a decrease by 10.4% in food consumption amount and 10.6% in body weight gain in the high drought treatment compared with the control. But the drought stress in wheat did not affect its food digestion by M.seperata larvae.Analyses of classical food utilization indices showed that the high drought stress treatment reduced the efficiency of conversion of digested food by 8.0%, but increased the approximate digestibility by 10.5% compared with the control. The results of this study suggested that moderate and heavy drought stress in wheat plants can decrease the food use efficiency by M. seperata larvae.