The crystal parameters and phase composition of Sm2Fe17Nx powders were investigated by means of XRD (X-ray Diffraction Test) and Rietveled method. The results show that the nitrogen atoms preferentially enter 9e crystal sites, and the introduction of them leads to the asymmetric distortion of SmFeN unit cell, resulting in that the occupancy of 6c and 3a sites for rare-earth Sm and 9d sites for Fe atoms are super-saturation, while the 6c, 18f and 18h sites for Fe atoms are possessed incompletely. After heated at 490 oC for 4 h under 0.3 MPa N2 atmosphere, the occupancy factor of nitrogen atoms in the 9e sites is 99.4% and the high-purity and high-nitrogen-content SmFeN powder with 97.9wt% main phase, 0.9wt% Sm2O3 phase, 0.5wt% SmN phase and 0.7wt% α-Fe phase are obtained.