Abstract: A method for the determination of pentachlorophenol (PCP) and hexachlorobenzene (HCB) in river sediments was established. Frozen-dried sediments analytes were pre-treated by ultrasonic wave extraction and acetyl derivation，followed by Florisil solidphaseextraction cleanup (Florisil SPE cleanup)，and then detected by gas chromatography-mass spectrometry (GC/MS) finally. The results presented a high accuracy and precision with the mean recoveries fell in 91%~99%, relative standard deviation lower than 10%. Method detection limits (dry weight) were 0.038 3 μg/g, 0.053 2 μg/g for PCP and HCB，respectively. Further more, a research was processed on the vertical distribution of PCP，HCB and total organic carbon (TOC) for the sampling sites. Accordingly, it is deduced that TOC is a possible important carrier of PCP and HCB vertical distribution in river sediments.