It was found that nickel had obvious catalysis effect on the fading reaction of chrome azurol S oxidized by hydrogen peroxide (H₂O₂) in NH₃-NH₄Cl buffer solution at pH 9.00. Thus, a new determination method of trace nickel in steel and alloy by catalytic kinetic spectrophotometry was established. The optimal determination conditions were obtained by experiments: the pH was 9.00; the reaction time in boiling water bath was 15 min in presence of 2.00 mL of 1×10^-2 mol/L chrome azurol S and 1.2 mL of 3% (V/V) H₂O₂. The influence of several common nonmetallic ions and metallic ions (such as Cl^-,NO^-₃,K⁺ and Na⁺) was investigated. It was found that most common ions had no or little influence on the determination. The interference of Fe³⁺ and Cu²⁺ in steel and alloy samples could be eliminated by adding NH₄F and KI solution. Under the optimized experimental conditions, the found maximum absorption peak of system was at 425 nm. The apparent activation energy of catalytic reaction was E_a=77.44 kJ/mol. The reaction rate constant was k=4.47×10^-4 s^-1. When the mass concentration of nickel was in range of 0.025-2.00 μg/mL, the linear regression equation of calibration curve was ΔA=0.083 6 ρ(μg/mL) -0.005 2 with correlation coefficient of r=0.998 3. The detection limit of nickel in proposed method was 0.007 μg/mL. The proposed method was applied to the determination of nickel in standard samples of steel and alloy. The found results were consistent with the certified values. The relative standard deviations (RSD, n=5) were between 1.2% and 2.1%.