Abstract: A laboratory experiment was conducted using the multiple-time superimposed and one-time pollution methods to investigate the degradation characteristics of chlorpyrifos in soil, bioaccumulation of chlorpyrifos in Amynthas corticis and its influence on growth of the earthworm. The results showed that the residue of chlorpyrifos in soil was more under one-time pollution condition than that under the multiple-time superimposed condition. When the soil was treated with 12-20 mg kg⁻¹ chlorpyrifos for 55 days, the concentration of chlorpyrifos in earthworm was measured to be 3.73-8.84 mg kg⁻¹ with the FBSA being in the range of 1.55-1.70 under one-time pollution condition; the concentration of chlorpyrifos in earthworm was measured to be 5.21-11.04 mg kg⁻¹ with the FBSA being in the range of 2.22-2.46 under the multiple-time superimposed condition. Compared with the one-time pollution methods, the accumulation of chlorpyrifos in earthworm increased significantly (P < 0.05), and the inhibition in growth increased significantly (P < 0.05) using the superimposed multi-time pollution when the soil was treated with the same concentration of chlorpyrifos. The findings of the research may serve as basic date for assessment to bio-toxicity and ecological risk of chlorpyrifos.