Superfine coatings have been attempted to prepare by Electro-spark deposition (ESD) on cast steel substrate. The microstructures and properties of the coating were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and microhardness tester. The results show that ultra-fine particles prevail in the coating. The primary phases of the coating contain Fe3W3C, Co3W3C, Si2W and W2C. Its average microhardness reaches 1511.75 HV. The results of abrasive test demonstrated that the coating had an excellent sliding wear resistance because the superfine particles distributed dispersedly in the coating increased the resistance to micro-cutting and plowing during the wear test, which effectively improves the surface performance of cast steel substrate.