Abstract: The castor plant leaf lost green, appeared scars,withered up and rolled up after being treated with 15μl/L air-phenol for 2～10h. The plant height,twig weight and output dropped by 9.9%,11.8% and 9.5% respectively, and the contents of chlorophyll, protein and dissolvable sugar for the leaf also dropped by 34.7%,3.8% and 42.8%, after being treated with 15μl/L air-phenol for 6h. The castor silkworm contacted 1μl/L air-phenol or ate castor leaf that contained 7～21mg/kg phenol during their larval stage, thus the larva-pupa rate,amount of laid eggs and hatchability dropped. When the worm contacted large than 8μl/L air-phenol or ate castor leaf that contained 45～70mg/kg phenol during their larval stage,it became slow in growth and development, bad in properties of cocoon and silk, and dropped in reproduction rate. The effects of the air-phenol were more serious than those of the plant-phenol. The resistance of castor silkworm to phenol increased with the larva growth.The toxicity of plant-phenol decreased, when the phenol-polluted leaf was treated with 5% limewater or the polluted leaf and normal leaf was feed alternately to the worm.