Abstract: To develop a novel colorimetric sensor for the rapid detection of hydrogen peroxide, single-atom Cu was immobilized on an ultrathin, nitrogenated two-dimensional carbon matrix via a thermal method, yielding a Cu-N-C nanozyme. This nanozyme was then characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The colorimetric sensor based on this nanozyme was used for the rapid detection of hydrogen peroxide in pork skin with pickled pepper. The results revealed that the Cu-N-C nanozyme exhibited excellent peroxidase activity, catalyzing the decomposition of H₂O₂ to generate hydroxyl (·OH) and superoxide anion radicals (O₂⁻·). These radicals were capable of oxidizing 3,3',5,5'-tetramethylbenzidine (TMB) to oxTMB, resulting in a distinct blue color. The colorimetric sensor based on Cu-N-C nanozyme was used for H₂O₂ detection with good selectivity, showing a good linear relationship in the range of 1~1000 μmol/L with a detection limit of 0.81 μmol/L. The detection results obtained by the developed sensor closely matched those obtained using national standard methods, indicating its effectiveness and suitability for the rapid detection of H₂O₂ in pork skin with pickled pepper. The proposed method has the advantages of simplicity, sensitivity and low cost, which can achieve the rapid detection of H₂O₂, showing a promising market prospect.