The electronic structures and magnetic properties of SmCo7-xMx;(M=Ti,si,Zr,Hf,Cu,B,Ag,Ga,Mn)com-pounds are investigated by using a spin-polarized MS-X.Q method.The results show that the long-range ferromagneticorder is determined by a stronger 3d-5d interaction,rather than the traditional RKKY interaction,and the effects ofdoping element M on 3d-5d coupling are negligible in Sm-Co-based compounds.The nonmagnetic dopant Si atomshave a larger effect on the moments of 2e site although they preferably occupy the Co 3g sites,which results in thestronger uniaxial anisotropy of this compound.Analysis of the formation energies indicates that 5d-element dopedcompounds are more stable than other dopants,and furthermore,they have a higher Curie temperature above roomtemperature,which will be in favor of their potential application as high-temperature permanent magnets.