The invention provides a preparation method of corn salt. The preparation method comprises the following steps: (A) putting corn grains in a table salt water solution, then adding sulfurous acid, andperforming soaking treatment and pulping to obtain corn pulp; sequentially performing homogenization, sterilization and spray drying on the corn pulp to obtain glutinous corn flour granules; (B) mixing 5-6 parts by mass of corn flour granules, 0-1 parts by mass of potassium citrate and 1-2 parts by mass of deionized water to obtain a mixed material; freezing the mixed material and then unfreezingthe frozen mixed material, and mixing the mixed material with 3-4 parts by mass of table salt to obtain a mixture; (C) extruding and puffing the mixture to obtain a corn salt precursor; and (D) spraying 0-1 part by mass of peppermint oil onto the surface of the corn salt precursor and performing drying to obtain the corn salt.