Abstract: To screen safety pesticides to Orius similis in tobacco fields, the toxicities of 7 kinds of pesticides on wingless adult of Myzus persicae (leaf immersion method), 5th instar nymph and female adults of O. similis (residual film method) was determined, and their safety to O. similis were evaluated. The results showed that the highest toxicity on M. persicae and female adult of O. similis was acetamiprid both at 24 h and 48 h, with LC₅₀ being 0.258 mg/L, 0.027 mg/L(24 h) and 0.164 mg/L, 0.019 mg/L(48 h) respectively, while the lowest toxicity was matrine, with LC₅₀ being 30.224 mg/L, 28.396 mg/L (24 h) and 17.106 mg/L, 9.334 mg/L (48 h) respectively. The toxicity of deltamethrin to 5th instar nymph of O. similis was the highest, and the toxicity of imidacloprid was the lowest. Abamectin and matrine had similar toxicities, which were only higher than imidacloprid. The results of toxicity and the safety coefficient indicated that if matrine and abamectin were used in controlling M. persicae, which would be better in protecting O. similis. These would achieve the objective of coordination of chemical control and biological control.