Abstract: In order to understand the chronic toxicity of pesticides to silkworm and establish chronic toxicity test and evaluation method of pesticides to silkworm, a systematic study on identifying administration phase, administration dose and evaluation indicator was carried out, using lambda-cyhalothrin,emamectin benzoate and hexaflumuron as representative pesticides. The results showed that in chronic toxicity test of pesticides to silkworm,the appropriate administration phase should be silkworm from second to third instar larvae, the appropriate administration dose should be 1/50, 1/100, 1/200, 1/400, 1/800 of the 96 h-LC50 value, and the main evaluation index should be cocooning rate of silkworm.