<p>Sm₅Co₁₉ permanent magnet alloy holds significant potential for applications due to its ultra-high intrinsic coercivity, low temperature coefficient of coercivity and high Curie temperature. However, its metastable nature poses challenges for experimental synthesis. Here we propose to use transition metal doping to effectively improve the structural stability and comprehensive magnetic properties of Sm₅Co₁₉ based on first-principles calculations. We find that Sc, Ti, V, Cr, Mn, and Zr preferentially occupy the Sm-6c2 site, while Fe, Ni, Cu, and Zn preferentially occupy the Co-6c2, Co-18h1, Co-18h2, and Co-18h2 site, respectively. Additionally, doping elements at their optimal sites significantly enhance the structural stability of the doped system. Whether substituting Sm or Co sites, doping with Cr, Mn, and Fe significantly increases the total magnetic moment of the Sm₅Co₁₉ system. Within the number of doping atoms range from 0 to 12, doping with Cr, Mn, and Fe enhances both the structural stability and the total magnetic moment of the Sm₅Co₁₉ system, further confirming the significant impact of atomic site occupation on the performance of the doped system. This study presents a feasible approach for enhancing the structural stability of Sm₅Co₁₉ permanent magnets and offers valuable theoretical guidance for the development of high-performance Sm-Co based permanent magnet materials.</p>