The contact action and the population inhibition against maize weevil imago with microbial pesticide emamectin benzoate by pesticide membrane method and mix round method was tested. The results showed that emamectin benzoate possesses a certain contact action and very strong population inhibition against maize weevil imago. The contact action significantly increased with the extending of time and the treatment concentration. The corrected percentage mortality was 40% after treatment by emamectin benzoate with the concentration of 16 μg/cm2 for 72 h. The inhibition of offspring population was better than that of contemporary. The inhibition of contemporary population of maize weevil treated by 16 mg/kg emamectin benzoate was 95%. The inhibition of offspring population of maize weevil treated by 4 mg/kg emamectin benzoate was 100%. The results provided the basis for reasonable application of microbial pesticide emamectin benzoate in biological control of pests in stored grain areas.