Abstract: Mo−Ni alloys were prepared by spark plasma sintering. The effects of sintering temperature, pressure, holding time, and heating rate on the relative density of Mo−Ni alloys were studied. The relative density, microstructure, and phase composition of Mo−Ni alloys were characterized by scanning electron microscope, X-ray diffraction, and electron back-scattered diffraction. The densification process of Mo−Ni alloys by spark plasma sintering was analyzed. The results show that, the sintering temperature and pressure are the main factors affecting the relative density of Mo−Ni alloys, the local high-speed diffusion of Mo and Ni is the main reason for promoting the densification of Mo−Ni alloys. The phases of sintered Mo−Ni alloys are mainly composed of Mo and Mo−Ni mesophases, and the Mo particles are evenly distributed in the network structure formed by Mo−Ni mesophases. The maximum relative density is 99.10%, the average grain size is less than 10 μm, and the average rockwell hardness value is HRA 72. The content of additive Ni does not change much before and after sintering.