The effect of entering of Fe-atoms and Sn-atoms into crystal lattice of permanent magnet SmCo5 on the X-ray diffraction relative intensities is studied. It is observed that the Fe-atoms can replace the Co-atoms on any site, but they replace Co2c more readily.However, the Sn-atoms replace the Co-atoms or 3 g sites more easily. The replacement of Co-atoms by the Sn-atoms can increases the ratio of X-ray diffraction relative intensity I200/I111, but the striking changes of this ratio is largely due to the alignment, the order of Fe, Sn atoms, the improvement of internal stress conditions, and the controlling of the ～750℃ phase transformation.