The invention discloses a preparation method of food anti-oil paper, and belongs to the field of paper making. The preparation method comprises the following steps: taking corn starch, water, alpha-amylase and calcium acetate, carrying out enzymatic hydrolysis and enzyme deactivation to obtain a zymolyte, taking 2,2,6,6-tetramethylpiperidinooxy, the zymolyte, sodium hypochlorite and sodium bromide, carrying out stirring and mixing to obtain a mixture, adding the mixture into an acetic acid buffer solution according to a mass ratio of 1:(60-70), carrying out stirring and mixing for 18-24h, introducing nitrogen gas, adding sodium periodate with a mass of 50-60% of the mass of the acetic acid buffer solution, carrying out heating to 40-50 DEG C, carrying out heat preservation for 3-5 hours, carrying out filtering, carrying out dialysis on the filter residue, carrying out freeze-drying to obtain a freeze-dried product, taking the freeze-dried product, adding water according to a mass ratioof 10:3, carrying out mixing by stirring for 30-40 min at a temperature of 55-65 DEG C to obtain a mixed liquid, taking the mixed liquid, coating a base paper surface of anti-oil paper according to acoating amount of 12-15 g/dm<2>, and carrying out drying to obtain the food anti-oil paper.