Abstract: Fe-Co alloys have high saturation magnetization and high Curie temperatures,while the addition of Pd can improve the magnetocrystalline anisotropy of the Fe-Co alloys,which is expected to obtain better magnetic materials. However,the study on the phase diagrams of the Fe-Pd-Co ternary alloys is very limited,and the order-disorder transitions in the Fe-Pd system as well as the miscibility gap in the Co-Pd system at lower temperatures are still uncertain,which limits the development of the Fe-Pd-Co alloys. In this study,the phase equilibria of the Fe-Pd and Co-Pd alloys below 700℃ was systematically investigated by using the diffusion triple approach,electron probe microanalysis (EPMA),scanning electron microscopy (SEM),and energy dispersive spectroscopy (EDS),and then the isothermal sections of the Fe-Pd-Co ternary system at both 500℃ and 700℃ were constructed. As a result,the Fe-Pd and Co-Pd binary phase diagrams have been reevaluated,with a particular focus on the FePd and FePd3 phases in the Fe-Pd system,as well as the miscibility gap in the Co-Pd system. Based on this,the phase equilibria and phase transformations of the Fe-Pd-Co alloys have been more thoroughly elucidated. These findings hold significant importance for the advancement and design of the Fe-Pd-Co ternary alloys.