The invention relates to a method for preparing a chitosan/cellulose blended membrane, and belongs to the field of natural polymer composite materials. The method for preparing the chitosan/cellulose blended membrane comprises the following steps: by taking an ionic liquid as a solvent, respectively dissolving cellulose and chitosan in the solvent, heating, stirring till the components are completely dissolved, mixing, and stirring uniformly so as to form a faint yellow or brown transparent solution; and performing vacuum defoamation on the mixed solution, pouring on a glass plate, scraping by using a membrane scraping rod, immersing the glass plate together with a blended membrane into a coagulating bath so as to obtain a gel blended membrane, washing, and drying, thereby obtaining the chitosan/cellulose blended membrane. The method provided by the invention is simple, low in cost and easy to operate, the ionic liquid is green, pollution-free and recyclable, and the prepared chitosan/cellulose blended membrane is dense in structure, good in mechanical property, good in biological compatibility and biodegradability, relatively good in inhibition effect on staphylococcus aureus, capable of promoting wound healing, and wide in application prospect in the fields of biological medical industry and food industry.