Abstract: The acute toxicity of twenty-seven pesticides to silkworm, Bombyx mori L., was evaluated in laboratory using Leaf dipping method; the grade was compartmentalized according as toxicity scope and the safety evaluation was made for these pesticides. The results indicate that the LC50 of two insecticides is lower than 0.1 mg/L(belong to special high toxicity grade); that of eight insecticides between 0.1~10 mg/L(belong to high toxicity grade); that of seven pesticides between 10~1 000 mg/L(belong to middling toxicity grade; that of ten pesticides higher than 1 000 mg/L(belong to low toxicity grade). And the method of toxicity determining of pesticide to silkworm was discussed.