The variations of sensitivity to several common insecticides of Spodoptera exigua(Hübner) after feeding on different host plants were measured in this study, which can be used as reference for the study of pest resistance, and provide theoretical evidence for the study of safety and economically utilization. The growth of S. exigua and its sensitivity to insecticides were apparently influenced by the host plants fed on. After feeding on different host plants, two strains of S. exigua exhibited different sensitivity to deltamethrin, chlorpyrifos, chlorfenapyr and tebufenozide. The results showed that pupal black mutation (melanism) strain had higher resistance than wild type, and both two strains had significant difference in the sensitivity to deltamethrin, in which the induced resistance ratio varied to 13.36 and 12.30 times, respectively. However, both two strains had no significant difference in the sensitivity to tebufenozide, in which the greatest induced resistance ratio reached to 2.54 and 2.23 times, respectively.