Abstract: Based on electrochemical biosensing technology, chitosan was used as bridge agent, combined with gold nanoparticles and horseradish peroxidase electrical signal amplification system, and FcεRI receptor protein was used as general molecular probe to adsorb anti-bovine milk α-casein antibody IgE, constructed a nano-gold immunosensor for the detection of allergen α-casein in bovine milk, and the milk α-casein was verified by time-current curve. The results showed that the kinetic equation of α-casein-IgE (immunoglobulins E) interaction conforms to the hyperbolic law, the results met the hyperbolic fitting criterion R²≥0.95, and had a substrate saturation effect similar to that of enzyme-substrate interaction. The value of the α-casein allosteric interaction constant (Ka) was 4.096×10⁻¹² mol/L calculated by referring to the Michaelis constant. The biosensor developed in this study could bind to the specific IgE of allergens and realize ultrasensitive detection of allergens. The detection method had high sensitivity, simple operation and low cost, and could provide a new detection method for allergic reactions caused by low-dose allergens.