The invention belongs to the technical field of intestine casing membrane processing, and relates to a collagen-and-wheat-protein combined edible intestine casing membrane and a preparation method thereof. The preparation method comprises the following steps as follows: firstly, material processing, to be specific, wheat protein is dissolved; secondly, mixed processing, to be specific, a wheat protein solution obtained from the step (1) is fully mixed with collagen, the pH value of the mixed solution is adjusted within a certain range, then a certain amount of a plasticizer and a cross-linking agent is put into the solution, stirred sufficiently and uniformly so as to obtain a membrane forming liquid; thirdly, membrane forming and drying, to be specific, the membrane forming liquid is subjected to tape casting and membrane forming, and is dried at certain temperature for a certain period of time so as to obtain an intestine casing membrane semi-finished product; fourthly, curing processing, to be specific, curing processing is carried out at a certain temperature and humidity conditions, so as to obtain an intestine casing membrane finished product. According to the invention, the prepared protein composite intestine casing membrane has the advantages of high tensile strength, high breakage elongation rate, high nutritional value, and the like.