A new catalytic kinetic spectrophotometry for the determination of trace copper was established based on the catalytic action of Cu2 on the oxidative fading reaction between 5-carboxy-1,3,4-triazole chlorophosphonazo (CTACPA) and H2O2 in the medium of HAc-NaAc at pH 4.0 and heating conditions. The maximum absorbance shows at 535 nm. The calibration curve was linear in the range of 0.004～0.2 mg/L for Cu2 , and the linear regression equation was ΔA=3.0260ρ-7.24?0-3 (ρ: μg/mL) with the correlation coefficient of 0.9994. The detection limit was 2.90?0-10 g/mL for copper. The method has bee applied to determine trace copper in hair and lake water samples. The results were in good agreement with the values obtained by atomic absorption spectrometry.