Abstract: In order to screen out the bacterial-drug blends with good compatibility and synergistic effect, through the feeding method, 66 strains isolated and purified from the soil in the Yongzhou area, as well as 13 strains preserved at the Biological Control Center of South China Agricultural University, were used to screen the highly virulent strains for the second instar larvae of Spodoptera litura,the highly virulent strains were assessed using different concentration gradients.At the same time, the mortality of emamectin benzoate, abamectin, spinosad, and chlorantraniliprole against the second instar larvae of insects was studied using different concentration gradients.When the spore suspension concentration of 79 strains was 1×10~8 conidia·mL^-1 and the second instar larvae of Spodoptera litura were treated for 7 days, the results showed that Beauveria bassiana SCAUYZ16 and SCAUJH19 had the highest virulence, with corrected mortality rates of 70.71% and 57.84%,LT₅₀ of 5.01 days and 5.98 days, respectively.The virulence of Beauveria bassiana SCAUYZ16 and SCAUJH19 were tested at concentration gradients of 1×10~4,1×10~5,1×10~6,1×10~7,and 1×10~8 conidia·mL^-1,with LC₅₀ values of 3.29×10~7 and 8.09×10~7 conidia·mL^-1,respectively.After treatment with emamectin benzoate, abamectin, spinosad and chlorantraniliprole on the second instar larvae of Spodoptera litura for 3 days, and the LC₅₀ were 3.56,59.14,18.82 and 2.76 mg·L^-1.SCAUYZ16 and SCAUJH19 showed a high level of virulence against Spodoptera litura and could be exploited as prospective Spodoptera litura biological control strains.The lower LC₅₀ dose of the pesticide can be used as the basis for the follow-up test, and different concentration gradients for the compound test of bacteria and pharmaceuticals can be adjusted.