Abstract: The sensitization effect of sodium dodecyl benzene sulfonate (SDBS) on the fluorescence of pyrene and anthracene was observed obviously,and the magnitude of increase in fluorescence intensity was found to keep linear relationships with the concentration of pyrene in the range of 4.9×10-9-5.0×10-8mol·L-1 and anthracene in the range of 5.6×10-9-5.6×10-8mol·L-1.Values of detection limit (3S/N) found were 7.4×10-10mol·L-1 for pyrene and 3.7×10-10mol·L-1 for anthracene.The reaction was used for determination of pyrene and anthracene and was applied to the analysis of river water,tap water and lake water,giving values of recovery in the range of 91.0%-102.0% (for pyrene) and 90.0%-111.1% (for anthracene).