The invention discloses a tungsten alloy and a preparation method thereof. The tungsten alloy is formed by mixing and sintering a tungsten matrix, Ni powder, Fe powder and Re powder, and the tungstenmatrix is W powder, coated powder and nickel powder. The method comprises the following steps of carrying out wet mixing, carrying out drying and sieving, carrying out wax mixing, carrying out dryingand sieving, carrying out forming; carrying out dewaxing/pre-sintering, carrying out sintering, and carrying out heat treatment after sintering. According to the tungsten alloy and the preparation method thereof, Re is a more effective solid solution strengthening element, so that the density of the alloy can be improved, and in addition, good plasticity can be maintained; in the whole sintering process, the nickel-iron binding phases are both in liquid phase, pores among tungsten particles are completely filled, and the capillary force formed by the liquid phase in the pores among the tungsten particles and the viscous flow of a liquid matrix phase enable the tungsten particles to be adjusted in position and to be uniformly distributed again; and Al2O3 powder with different particle diameters is added, so that under the premise that certain dynamic compression strength and plasticity of the tungsten alloy are guaranteed, the tensile strength can be reduced, the fragility of the material can be improved, and the purpose of secondary damage caused by the fact that fragments are formed after the tungsten alloy material is pierced can be guaranteed.