The invention discloses a mite resistant finishing method for a cotton fabric. The method comprises the following steps: firstly adding water into a finishing agent to prepare an aqueous solution, then spraying the aqueous solution on the surface of the fabric through a high-pressure spraying technology, and finally performing drying. The finishing agent is prepared from the following components in parts by weight: 50-60 parts of water, 8-10 parts of sodium polystyrene sulfonate, 6-8 parts of diatomite, 15-20 parts of 2-methyl-4-isothiazolin-ketone, 6-9 parts of sodium citrate, 11-14 parts of garlic juice, 12-14 parts of colloidal-state silicon dioxide, 2-6 parts of potassium oxalate, 3-5 parts of turpentine, 3-5 parts of benzyltrimethylammonium chloride, 2-4 parts of cinnamic aldehyde, 3-7 parts of didecyldimonium chloride, and 4-7 parts of ammonium perchlorate. The mite resistant finishing method for the cotton fabric, disclosed by the invention, is safe and effective, the cotton fabric prepared by the finishing method disclosed by the invention has favorable properties of driving away and repelling dust mites, gamasid and chigger, after the fabric is in contact with skin surfaces for a long term, the cotton fabric is safe and free from stimulus, and a comfortable family living environment is created for people.