Abstract: The high-entropy alloy FeCrMnNiAl_x (x=0, 0.1)was prepared by vacuum induction melting technology and then was heat treated. The phase composition, microstructure and tensile properties of the alloy were measured and characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM)and universal tensile testing machine, respectively.The results show that FeCrMnNiAl_x(x=0, 0.1)alloys are all FCC+BCC two-phase solid solution alloys, and Al atoms are dissolved into the matrix alloy in the form of interstitial atoms.When Al is added, the dendritic structure of the alloy is transformed into an island structure, and the micron-size needle-like second phase is formed there.After heat treatment, the second phase is transformed from micron-size needle like to nanometer granular. The addition of Al effectively enhances the strength of the high-entropy alloy.After heat treatment at 800 ℃, the tensile strength and yield strength of FeCrMnNiAl_0.1 high-entropy alloy are increased by 31.7% and 17.5%, respectively than that of as cast state, and the alloy still has about 21.1% elongation. Proper heat treatment can improve the comprehensive mechanical properties of high-entropy alloy.