Abstract: Using 0.5 mm×3.0 mm carbon rod as substrate, PdCl₂ as precursor, ¹⁰³Pd as radioactive tracer, and hydrazine as reductant, the process of electroless ¹⁰³Pd-plating was studied. The results show that the optimum conditions of electroless ¹⁰³Pd-plating are 2 g/L PdCl₂, 65 g/L Na₂EDTA, 700 mL/L 25%NH₃•H₂O, 100 mL/L 5%H₄N₂•H₂O, pH=10, t＝90 min, and the temperature of 50 ℃. The solution has good stability. The electroless ¹⁰³Pd-plating is easy to carry out. About 95% ¹⁰³Pd is deposited and 12% activity is shielded by the carbon rod. The utilization rate of ¹⁰³Pd in the chemical adsorption reaction is high. ¹⁰³Pd-coating is grey and smooth. ¹⁰³Pd-coating on each substrate of carbon rod is uniform, and the reaction can be repeated well. The technology of electroless ¹⁰³Pd-plating can be applied in preparation of ¹⁰³Pd seed and ¹⁰³Pd-¹²⁵I hybrid seed which is a new member of brachytherapy.