The invention discloses a preparing method for a silver and copper composite belt. The preparing method includes the specific steps that firstly, a copper plate is rolled, a surface is subjected to rolling treatment, then cutting is conduced, the surface is cleaned, and the copper plate is fixed in a casting die; secondly, a silver ingot is subjected to secondary degassing smelting in a vacuum smelting furnace, a silver solution is poured into a prepared die, the copper plate is wrapped by the silver solution, the copper plate is taken out to be cooled, surface impurities are removed, vacuum diffusion treatment is conducted under the temperature of 400 DEG C to 650 DEG C, and a silver and copper composite blank is obtained; and thirdly, the silver and copper composite blank in the second step is subjected to width cutting on a shearing machine, and the silver and copper composite belt is obtained. By means of the preparing method for the silver and copper composite belt, the whole process for preparing the silver and copper composite belt is completed under the vacuum condition, the problem of material oxidization is avoided, the combination degree of the belt is high, use of previous metal materials is saved, the product cost is greatly reduced, and very high economic benefits and huge social benefits are achieved.