The invention belongs to the field of nuclear materials, and particularly relates to a
nuclear fuel and a preparation method thereof and a reactor, the
nuclear fuel comprises a
nitride matrix and an MAX phase material distributed in the
nitride matrix; the
chemical formula of the MAX phase material is Mn + 1AXn, M is selected from at least one of Ti and Cr, A is selected from at least one of Si and Al, X is selected from C, and n is 1 or 2. According to the
nuclear fuel disclosed by the invention, the MAX phase material is introduced into the
nitride matrix, and a
corrosion-resistant
oxide layer is generated in situ by utilizing the MAX phase material to block water
permeation, so that the nuclear fuel has the properties of high
thermal conductivity, relatively strong water
corrosion resistance, steam
oxidation resistance and
radiation resistance, and can be applied to a
light water reactor; the application risk of the existing
uranium nitride fuel in the light-water reactor is reduced, and the safety and economy of the reactor are improved.