The compositions of humic acids(HAs) in various soils were common in nature,but the aromatic structures,function groups,molecular weight,and the level of HAs from various soils were significantly different.On these base,the influences of HAs on hydrolysis of phoxim were studied.The results showed that the hydrolysis effect differed for soils that contained different level of HAs. With the concentration of HAs increasing,hydrolysis of phoxim decreased gradually,and the effect by acid purple soil with the lower level of HAs was distinct.Therefore,it may be conferred that the speed of hydrolysis of phoxim was related to the concentration of HAs and the level of HAs.