The combined effects of (Y, Cu) on the microstructure and room-temperature mechanical properties of the NiAl intermetallic compound under uniaxial compression stress were investigated. It is found that the co-addition of Y and Cu enlarges the difference between the intergranular yield strength and the intragranular yield strength of NiAl grains. Hence, for the resultant NiAl-(Y,Cu) alloy, a mechanically hierarchical structure forms. This is beneficial to improve the room-temperature mechanical response of NiAl alloys; as a result, the resultant alloy with 0.56at% (Y, Cu) exhibits a remarkably enhanced compression plasticity of about 11.2%.