Abstract: Based on the fact that an enhancing effect on the fluorenscence intensity of dimethyl phthalate (DMPT) by the presence of Tween-20 in an alkaline solution,a method for the fluorophotometric determination of DMPT in water was established.The excitation and emission wavelengths of this fluorescence reaction were found to be 282 nm (λex) and 369 nm (λem).Linear relationship between the magnitude of enhanced fluorescence intensity and the concentration of DMPT in the range of 0.02-7.0 mg per L of solution.Recoveries in range from 96.7% to 106.5% were obtained.Detection limit of the method was 0.01 mg·L-1.RSD (n=7) of 2.7% was found in the analysis of water samples taken from the Suzhou Creek in shanghai.