Abstract: The sample of soil was extracted with NaOH,in which water-insoluble pentachlorophenol (PCP) was transformed into water-soluble PCP-Na,and determined by UV spectrophotometry.Influential factors,including pH value of medium,ratio of solid to liquid and time of extraction were studied.Under the optimum condition,linear relationship between values of absorbance and mass concentration of PCP-Na was kept in the range within 40 mg·L-1,with detection limit (3S/N) of 0.023 mg·L-1.Test for accuracy was made by standard addition method,and values of recovery obtained were in the range of 94.4%-104.7%.