The invention relates to a preparation method of an insect-resistant and anti-mildew preservative for bean curd sticks. The insect-resistant and anti-mildew preservative is prepared by mixing and packaging microencapsulated clove oil, sweet orange oil and sodium pyrosulfite in weight ratio. A preparation method of microencapsulated clove oil and sweet orange oil comprises the following steps of: proportionally dissolving sodium alginate in water, adding clove oil and sweet orange oil, adding an emulsifying agent, and agitating for 15 min at room temperature by using an agitator at the speed of 300 r/min; adding the emulsified liquid into a 2% CaCl2 solution, agitating for 10 mi, filtering after agglomeration, drying in a vacuum drying oven to obtain faint yellow matter, crushing and sieving through a 200-mesh screen; and dissolving ethyl cellulose in ethanol, adding corn starch, dissolving, agitating for 20 min, adding the emulsifying agent and sodium pyrosulfite, homogenizing at 70-80 DEG C, performing spray drying, mixing the product with a certain amount of paraffin wax by maintaining the temperature at 60 DEG C, cooling and drying. The microencapsulated clove oil, the microencapsulated sweet orange oil and the microencapsulated sodium pyrosulfite are proportionally mixed, tabletted and packaged to obtain the preservative.