Histamine is a class of potentially harmful biogenic amines produced during the storage and processing of meat products. Its content is a key indicator for evaluating food freshness and safety. In order to meet the needs of rapid and sensitive detection of histamine in meat products, an electrochemical biosensor based on diamine oxidase (DAO) and graphite carbon nitride / titanium dioxide (g-C3N4/TiO2) heterojunction was constructed. The g-C3N4/TiO2 heterojunction material was prepared by one-step calcination method, and the structure was characterized by scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. It was confirmed that TiO2 nanoparticles were uniformly loaded on the surface of g-C3N4 nanosheets, and a stable heterojunction interface was formed between them. Density functional theory calculations further confirmed that the heterojunction interface can effectively enhance histamine adsorption and promote interfacial charge transfer. Based on the theoretical calculation, the analysis of the heterojunction enhanced histamine absorption mechanism shows that the sensor enhances the enzyme immobilization efficiency and constructs an efficient electron transport channel, thereby realizing the effective conversion and amplification of the biological recognition signal to the electrochemical signal.The results showed that the sensor had a good linear relationship in the range of 0.05-9.00 mmol/L, the detection limit was 0.226 μmol/L(S/N=3), and the response interference deviation was less than 8% in the anti-interference experiment. In the actual meat sample detection, the relative standard deviation was less than 5%, showing good accuracy and reproducibility. The DAO/g-C3N4/TiO2 biosensor constructed in this study can be used for rapid screening and quantitative detection of histamine in meat products, aiming to provide a stable and reliable technical means for the accurate detection of histamine in food.