The invention relates to a food processing method, in particular to a method for manufacturing high-calcium slimming kidney bean noodles through mushroom salting water. Cucumbers are squeezed to obtain cucumber juice, superfine grinding is performed on kidney bean powder, the mushroom salting water is filtered and concentrated, the pH value of the mushroom salting water is adjusted, the mushroom salting water is sterilized, 25-30 parts of kidney bean powder, 10-36 parts of wheat flour, 10-15 parts of cucumber juice, 29-45 parts of mushroom salting water, 1.5-3 parts of edible salt and 0.05-0.1 part of edible alkali are mixed for flour mixing, dough is naturally rested and cut into the noodles through secondary dough pressing, and the products are obtained through vacuum freeze drying. According to the method, rich nutrients of the mushroom salting water are sufficiently utilized, waste of available resources is avoided, and the conception of turning waste into wealth is realized. In addition, kidney beans serve as main raw materials, the nutrients of the noodles are strengthened, the coarse food grain noodles have the advantages of being high in protein and calcium ferrite, low in sodium and the like, are easier to digest and absorb by the intestines and stomach, have the effects of beatifying and slimming as the cucumber juice is added, are beneficial to improving digestion if eaten for a long time, and therefore the effects of slimming and beatifying are achieved.