Abstract: In a weak-acid solution, titanium was found to be able to react with stilbazo and cetyl-trimethyl ammonium bromide(CTMAB), forming a red ternary complex. The wavelength of maximum absorbance for the complex was 520nm.The molar ratios of the components in the complex are estimated to be Ti (Ⅳ): stilbazo :CTMAB = 1:3 : 6. The present method can be applied to the determination of trace Ti in water. A 5cm cell was used in the spectrophotometric determination, the molar absorptivity was 1.1×10⁵ at 520 nm. The calibration curve well follows Beer's law in the range from 0 to 0.75 μg of Ti (Ⅳ) in 25 ml solution under the above condition. It was found that the method proposed in this work had high sensitivity and gave gratifying result in the determination of Ti (Ⅳ) in water.