Abstract: The toxicity of five kinds of protective agent, deltamethrin (2.5%), natural pyrethrins (3%), azadirachtin (0.3%), Resigen, beta-cyglathrin (4.5%) and two mixed pesticides (C and D, main active ingredient:pyrethroid) against tobacco beetle (Lasioderma serricorne) were determined.The results showed that:1) the LD50 of deltamethrin, beta-cypermethrin, pesticides C and D were 1.3457×10^-3, 2.7991×10^-3, 2.8672×10^-3, 2.0486×10^-3μg per beetle, respectively;2) the contact toxicity of pesticides C and D was outstanding killed all the adult tobacco beetles in 24 hours at a concentration of 1.05mg/m2, followed by deltamethrin, and azadirachtin and Resigen were the least.