The invention discloses a preparation method of a metallic fuel pellet with high irradiation stability. The preparation method comprises the following steps: firstly, mixing uranium-based alloy powderand a carbon-based nanomaterial according to the volume ratio of (99.9-99):(1-0.1), then, placing the mixture into a nylon ball milling tank, adding zirconia grinding balls of which the mass is 3 times as high as that of the mixture, and carrying out mixing for 24h to obtain a mixed powder; and secondly, carrying out pressureless sintering, hot pressed sintering, spark plasma sintering or flash sintering on the mixed powder, after heat preservation and pressure preservation, carrying out furnace cooling, taking out the cooled material, and then, processing and molding the cooled material to obtain the metallic fuel pellet. The metallic fuel pellet obtained by using the method has the advantages of high uranium loading capacity, high heat conductivity, good anti-irradiation properties, strong fission gas accommodating capacity and excellent mechanical properties and can be used as a novel nuclear fuel of a nuclear reactor.