In order to explore the effects of relative humidity (RH) on the population growth of summer fruit tortrix moth Adoxophyes orana, the development, survival, fecundity and longevity of A. orana were assessed at 6 different constant humidities (40%, 50%, 60%, 70%, 80% and 90%), (25±1) ℃ and a photoperiod of 12L:12D in the laboratory. The results showed that immature developmental time was gradually shortened with the increasing humidity at 40%-90%RH, ranged from 30.31 d at 40%RH to 25.87 d at 90%RH. However, the survival rate for immature moth was gradually increased from 40%RH to 90%RH. Hatchability was inhibited significantly by low humidity and the lowest was 39.3% at 40%RH. And at 80% RH, the longevity of adults was the longest, the oviposition was the most (110.8 eggs per female), and the survival rates for eggs and larvae were the highest. It resulted in the highest net reproductive rate (R₀=26.46) and intrinsic rate of increase (r_m=0.1018). In conclusion, the development and fecundity of A. orana were promoted and improved at the higher humidity.