Abstract: Nickel-63 radioactive sources used in micro nuclear batteries require high surface emissivity, thin coating and small substrate. The method for the preparation of nickel-63 radioactive sources by direct and constant current electrodeposition was established by using nickel-63 solution with small volume, high specific activity and low Ni²⁺ concentration as electrodeposition liquid.Using this method, under the conditions of copper substrate, Ni²⁺ concentration with 1 g/L, electrodeposition pH with 3.5-4.5 and sulphamic acid concentration with 0.1 g/L, the electrodeposition efficiency can reach to 95.8% after 1 h. The coating is compact and bright with the thickness from 0.3 μm to 1.6 μm. The surface emissivity of the prepared nickel-63 radio-source film is up to 2.40×10⁷ s^-1·(2πSr)^-1 while the activity is up to 1.89×10⁹ Bq, which can meet the application requirements of micro nuclear batteries. At the same time, by recovering the residual electrodeposition solution and adjusting its composition, the reuse of electrodeposition liquid is realized, reducing the waste of nickel-63 raw material.