The invention relates to a magnetic refrigeration material and a preparation method thereof. The magnetic refrigeration material comprises a basal body consisting of Mn, Co and Ge, and Sn doped in thebasal body; and the mole percentage of Sn is 0.02-0.7%. The preparation method of the material comprises the following steps: (1) simple substance metals of Mn, Co, Ge and Sn are weighed for fusion mixing under an inert gas environment to obtain a mixed sample; and (2) the mixed sample is annealed to obtain the magnetic refrigeration material. Compared with the prior art, the temperatures of structural phase transition and magnetic phase transition of alloys and the magnetothermal effects near phase transition points are prominently improved; and the MnCoGeSn alloy magnetic refrigeration material has the advantages of low heat stagnation, high magnetothermal effect, simple preparation and the like, can provide preparation parameters for development of magnetic refrigeration, and can be applied to petrochemical engineering, electric power industry, precise instruments, aerospace, medical equipment and the like.