In order to improve wear resistance of engine cylinder, the surface hardening technology is analyzed. The hardening methods which iron plating and composite iron plating have application in engine cylinder repair are put forward. The relative speed and pressure between piston ring and cylinder wall are determined as main wear factors of engine cylinder. And wear resistance of hardening material is chosen as assessment index. At the high load, the relative wear resistance of engine cylinder hardened by composite iron plating is twice as high as high phosphors cast iron. By comprehensive contrast of the wear resistance of hardening materials, relative wear resistance of composite iron plating is better than common engine cylinder material, and can fit for the cylinder hardening of high load engine.