Objective To obtain a Ni201 restoration layer with a better quality by electro-spark deposition. Methods Using electro-spark deposition technology, Ni201 restoration layer was prepared on Q235 steel surface with the DHD-6000 type electrospark deposition equipment, the microstructure, chemical elements distribution, phase composition of the bonding interface between the restoration layer and the substrate, and residual stress on the surface of the restoration layer were investigated by means of scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction. Results The microstructure of Ni201 restoration layer was uniform and dense, and there was interdiffusion of elements between the restoration layer and the substrate, the main phases of the restoration layer bonding interface were composed of Fe10. 8Ni, γ( Fe,Ni), CoFe15. 7 and Fe, the residual stress on the surface of the restoration layer increased with the increase of power output amplitude, the residual stress was -38. 1 MPa and -81. 6 MPa under the conditions of 40% and 45% energy output, respectively, and the value of residual stress was low. Conclusion The interdiffusion of elements between the Ni201 restoration layer and the Q235 steel substrate indicated formation of metallurgical bonding between the substrate and the restoration layer, and the Ni201 restoration layer was a metallurgical bonding layer. The key factor for the quality of the restoration layer was determined by the process parameters selection of remanufacturing repair equipment, and the quality of the restoration layer prepared with an energy output amplitude of 40% was better than that prepared with an energy output amplitude of 45% .