Abstract: Neodymium(Ⅲ) reacted with 7-lodo-8-hydroxyquinoline-5-sulfonic acid and cetyl-trimethylammonium bromide to form a associated complex in NaAc-HAc(pH=5.00) buffer solution. The apparent molar absorptivity of the associated complex was found to be 1.8×10⁴ L/(mol·cm) at 389.50 nm. In the range of 0.2 to 4.0 mg/L, Neodymium(Ⅲ) obeyed Beer's law. The linear regresion equation was ΔA=0.1205C+0.0052, r=0.9996. Where C is mg/L of Neodymium(Ⅲ). The RSD for the determination of 2 μg/ml of Neodymium(Ⅲ) was 5.0‰(n=8).The molar ratio of Neodymium(Ⅲ) to cetyl trimethylammonium bromide to 7-lodo-8-hydroxy-quinoline-5-sulfonic acid in association complex was establish to be 1:2:2.The influence of 20 diverse ions was examined. Most common ions did not interfere.The method was proved to be satisfactory for the determination of Neodymium(Ⅲ) in recovery.