Abstract: In order to control pests in tobacco field more effectively, the control efficacy of a biological pesticide, 4% "Lishasi" EC, was tested against tobacco budworm and aphid in laboratory and tobacco field.The results indicated that the LC₅₀ of 4% "Lishasi" EC at a dilution of 2500 against tobacco budworm and aphid was 0.896 mg/L and 0.03mg/L, respectively;and the control effect against aphid was better than that against budworm.For the aphid, the corrected control rate of 4% "Lishasi" EC at a dilution of 2500 was over 98% in 4 and 6 days after applying in field;while for the budworm, it was 79.4% in 5 days after applying.There was no obvious difference in control effect between "Lishasi" and methamidophos.