Based on first principles full potential linear muffin-tin orbital method within the local density approximation, we have studied the structural, elastic, electronic properties and the behaviour under pressure on the magnetic moments per atoms from 0 to 85 GPa for YFe2, NiFe2 and YNiFe4 intermetallic. The magnetic per formula unit value and equilibrium lattice constant of YFe2 are calculated and compared with experimental data and theoretical results. However, this is the first predictive calculations for the structural and magnetic properties for NiFe2 and YNiFe4 compounds. From the computed elastic constants, theoretical value of Young’s modulus, Shear modulus, Poisson’s ratio and Lamé’s coefficients, sound velocities and Debye temperature are evaluated. Our results demonstrate that NiFe2, YFe2 in C15 phase and NiYFe4 in C15b phase are mechanically stable with the large bulk moduli B0 = BVR for alloys containing atom Ni (NiFe2 = 224.7 GPa and NiYFe4 = 192.0 GPa). Finally, we have calculated the total and partial density of states for the three compounds. The partial density of states shows strong hybridization at Fermi level.