Changes of hardness of B2-NiAl(Fe) intermetallic compounds in Ni-Al-Fe system with aging time and changes of yield strength of aged B2-NiAl(Fe) intermetallic compounds containing α-Fe precipitates with temperatures were investigated. Results show that the yield strength of B2-NiAl(Fe) intermetallic compounds containing α-Fe precipitates is higher than that of single phase NiAl at all the testing temperatures. It is revealed that the precipitates are disordered bcc Fe phase. The shape of α-Fe precipitates is sphericity and keeps coherent with the matrix in the initial aging period. With prolonging the aging time, the precipitates are platelet in shape, nearly parallel to the {100} planes of the B2-ordered matrix. TEM observation determines that the Burgers vector of the slipping dislocation is <111>. Although the hardness of α-Fe precipitates is lower than that of B2-NiAl(Fe) matrix, the pinning effect of the α-Fe precipitates on moving dislocation plays an important role in hardening of the B2-NiAl(Fe) matrix.