Abstract: By using the ultraviolet absorption spectrum to detect the change of absorption value of CaO₂ at 288 nm, a fast and accurate method of CaO₂ detecting in flour was established. The results showed that when the Mb-Cu concentration was 3.9×10⁻⁶ mol/L, the detection temperature was 60 ℃, and the detection time was 180 s, the CaO₂ concentration was linear with the change in absorbance at 288 nm, and the linear equation was y=0.00643+0.02117x, R²=0.99281. The detection limit of the method was 1.82×10⁻² mg/L, the average recovery of standard addition was 98.2%～100.6%, and the relative standard deviation RSD was 0.49%～1.32%. This Mb-Cu mimic peroxidase method has high accuracy, fast detection speed, and low detection limit. It can be used in practice for the trace detection of CaO₂ in flour, providing a new strategy for the food detection industry.