The invention belongs to the technical field of material forming and preparation processes of magnetron sputtering alloy targets, and provides a Ni-Mn-Sb alloy material and a spark plasma sintering preparation method thereof. The preparation process includes the following steps that Ni, Mn and Sb raw materials are weighed according to the raw material ratio, vacuum arcs are used for repeated smelting, a polycrystal cast ingot is prepared, the polycrystal cast ingot is ground into powder through a grinder, the powder is put in a graphite grinding tool, and the powder is sintered in the vacuum environment in a spark plasma sintering system, wherein the heating speed is 30-100 DEG C/min, the pressure is 40-80 MPa, the sintering temperature is 600-950 DEG C, and the heat preserving time is 5-20 min. The process is simple, and the prepared Ni-Mn-Sb alloy has excellent mechanical performance.