Abstract: Under laboratory conditions, degradation of cypermeth rinin 3 soils including terranera soil from Northeast China, cinnamon soil from North China, and terrarossa soil from South China was studied. The above 3 type of soils were amended with cypermeth in for 3 times in a ca. 60-day interval. The results showed that the bio-degradation of cypermethrin in these 3 soilsw asplaying a leading role, and the chemical degrada-tion was subsidiary. The rates of the chemical degradation didn′t differ greatly from each other as there were differences of the physical and chemical properties between these soils. The DT50 s of cypermethrin in soils were enlarged by the following successive amendments of cypermethrin, as the more hardly degradable cis-cypermethrin accumulated.