Abstract: The laser alloying technique was applied to the high-Ni-Cr infinite chilled cast iron roller coated with nano-carbide ceramics. The microstructural morphology, composition, cross-sectional microhardness distribution and the phases of the alloyed coating were analyzed by OM, SEM, microhardness tester and XRD. The results revealed that the flat alloyed coating combines metallurgically with the substrate with some cracks found in part. Under conditions that the laser power, spot diameter and overlap ratio remain unchanged, the thickness of the coating changes slightly with varying scanning speed, but the rate of cracks increases with increasing speed and the hardness of alloyed coating increases then decreases with increasing scanning speed. The optimal scanning speed is 11 m/min when the laser power is 7.2 kW, beam diameter 0.8-3 mm and overlapping rate 33.3%. At the moment, the average thickness of alloyed coating is 0.2875 mm with an average microhardness up to 1001 HV0.05, i.e. about 1.53 times as high as that of the substrate of 656 HV.