Abstract: In an acetate buffer medium of pH 5.5,a stable red colored complex was formed between gallium(Ⅲ) and p-chlorophenylfluorone (p-ClPF) in the presence of CTMAB which remarkably sensitized the color reaction,giving a bathochromic shift from (λmax) 530 nm of the complex in the absence of CTMAB to (λmax) 571 nm in the presence of CTMAB and making an increase of molar absorptivity (ε571=1.17×105L·mol-1·cm-1) about 10 times greater. Beer′s law was kept in the range with in 8 μg of Ga(Ⅲ) per 25 mL of solution. In its application to the analysis of zinc slag,a preliminary separation of Ga(Ⅲ) from the interfering ions,by TBP-kerosene extraction and NH4Cl solution-back extraction of Ga(Ⅲ) was necessary to improve the selectivity of the method. Recovery and RSD′s obtained in the analysis of substantial samples of zinc slag and crude zinc oxide were in the ranges of 97.6%-102.5% and 1.6%-2.6% respectively.