Abstract:FePt nanoparticles with face centered tetragonal phase (L10) structure have the characteristics of large Magnetocrystalline anisotropy, good biocompatibility and high catalytic activity, and have broad application prospects in the fields of information storage, military, catalysts, permanent magnets and biomedicine. The research shows that the addition of precious metals or transition metal elements such as Au, Ag, Cu can simplify the preparation process, significantly reduce the disorder order transition temperature of L10 FePt nanoparticles, and induce the one-step synthesis of highly ordered L10 FePt nanoparticles. In this paper, we doped the third metal element Pb, and directly synthesized L10 FePt nanoparticles with uniform composition, no agglomeration, high order and good magnetic properties through wet chemical method. The results showed that the ordering degree s and coercivity Hc of L10 FePt nanoparticles increased with the increase of reaction temperature. The best synthesis temperature is 360℃, and L10 FePt nanoparticles with the best magnetic properties can be prepared. At this time, the atomic composition of the nanoparticles is Fe62Pt15Pb23, and the coercivity after pickling is Hc=8622.4 Oe. Therefore, L10 FePt nanoparticles with high order and good dispersion can be directly synthesized by a reasonable synthesis process and the induction of the third element. The one-step synthesis process of Pb elements is expected to achieve the controllable preparation of L10-FePt nanoparticles.