Abstract: Chromogenic reaction of alizarin yellow GG with ferric ion in an ammoniacal buffer of pH 8.0-10.0 and in the presence of CPB was studied by spectrophotometry.A red complex with mole ratio of 3 to 1 between alizarin yellow GG and Fe(Ⅲ) was formed,having its absorption maximum at the wavelength of 470 nm,at where the apparent molar absorptivity was found to be 5.281×104L·mol-1·cm-1.Beer′s law was held in the range within 1.0 mg·L-1 of Fe(Ⅲ).The proposed method was used in the determination of iron in aluminum and aluminum alloys,with the results found in consistency with the known values,and giving values of RSD′s (n=8) less than 3%.