Belonging to the technical field of solid instant beverages, the invention relates to a walnut polypeptide coffee and a preparation method thereof. The walnut polypeptide coffee mate includes two major raw materials: instant coffee and walnut mate powder. The walnut mate powder is prepared from the following raw materials: walnut oil, walnut polypeptide powder, xylitol powder, fructooligosaccharide, maltodextrin, sodium caseinate, silica, monoglyceride, sodium stearyl lactate, sodium tripolyphosphate, lecithin, tripolyglycerol monostearate and propylene glycol monostearate. The walnut polypeptide coffee provided by the invention is not added with coffee creamer, vegetable fat powder, white granulated sugar or other ingredients, uses walnut grease to replace vegetable fat powder, and is added with walnut polypeptide powder. As walnut polypeptide powder has the functions of enhancing immunity, resisting oxidation, lowering blood pressure, restoring fatigue and the like, the coffee mate prepared from walnut polypeptide powder can endow coffee with a series of nutritional and health care functions, and the product can be more in line with the requirements of modern nutritional diet. Atthe same time, the walnut polypeptide coffee provided by the invention turns waste into treasure, improves the added value of walnut meal, and is easy for popularization and application.