The invention relates to a preparation method of a low-melting-point alloy phase change material, and belongs to the technical field of preparation of phase change materials. The method comprises the following steps: removing surface oxides of raw materials Ga, In and metal A, wherein the metal A is one or more of Sn, Bi, Zn and Al; adding Ga, In and metal A into a smelting medium, increasing the temperature to a preset temperature at a constant speed, conducting heat preservation for 4-6 hours, and conducting metal alloying to obtain an alloying system, wherein the smelting medium is glycerol or silicone oil; and heating the alloying system to the preset temperature, performing uniform stirring and mixing to performing full alloying, and then adding an ice-water mixture into the alloying system to quickly cool an alloy sample and obtain the low-melting-point alloy phase change material. According to the method, the glycerol or silicone oil is adopted as the smelting medium, the problems of oxidation, insufficient alloying and the like of low-melting-point alloy in the smelting process can be effectively solved, the low-melting-point alloy phase change material has greater latent heat in unit volume, the heat capacity of the low-melting-point alloy phase change material can be greatly improved, the volume proportion of the phase change material is effectively reduced, and better stability and higher heat conductivity are achieved.