Abstract: DW-spectrophotometry was applied to the simultaneous determination of salicylaldehyde (SAD) and phenol (PHN) in water.As shown in the UV absorption spectra,an iso-absorption point at 271 nm was found in the absorption spectra of SAD,and the absorption maximum of SAD was found at the wavelength of 328 nm,while the absorption maximum of phenol were found at 271 nm and 278 nm.In the present method,the wavelengths of 328 nm and 271 nm were chosen as the wavelengths of determination of SAD and PHN respectively,and their contents in mass concentration (g·L-1) were found by the following simultaneous equations which were based on their regression equations: CSAD=31.31 A328 nm+0.344;CPHN=44.53 A271 nm-1.866 A328 nm-0.136.For both compounds,the linearity range was kept between 0.005-0.030 g·L-1.