Abstract: In order to find a rapid, simple and sensitive method for determination of iodine in food, a gold nanoparticle modified electrode was constructed by cyclic voltammetry (CV) to detect iodine ion (I^-). In situ reduction of gold nanoparticles (Mb@AuNPs) using methanobactin (Mb), and the self-assembled modified electrode was preparaed by electrodeposition. Mb@AuNPs was characterized by transmission electron microscope (TEM), the electrochemical behavior of iodine ion (I^-) was investigated by CV. The optimized conditions for iodine ion detection were as follows: Electrodeposition scanning rate 0.11 V/s, number of scanning cycles 30, buffer concentration 0.05 mol/L, buffer pH 6.5. There was a good linear relationship between oxidation peak current and I^- concentration in the range of 0.01~10.00 μmol/L, R² was 0.9992. The detection limit was 2.88 nmol/L (S/N), and the quantitation limit was 9.60 nmol/L. The recoveries of iodine content in different foods were 96.22%~103.57%. The results show that the modified electrode has good precision, stability, reproducibility and anti-interference ability for the determination of I^-, which meets the requirements of the determination method and can be used for the determination of I^- in practical samples.