Cr5 series back-up roll was remelted by fiber laser in this study. Through the analysis of structure,micro-hardness and wear resistance,the influence of laser power and scanning speed on single-pass remelted layer,as well as the influence of laser power and scanning distance on multi-pass remelted layer were studied. The result indicates that laser remelting can improve the surface performance greatly,the microhardness reaches 800 HV for single pass processing. The remelted layer has been softened by the later laser pass in the multi-passes processing. But it has good thermal stability,the average microhardness can reach about 600～700 HV,the wear resistance increases about 10 times after the fiber laser remelted. Under this condition of experiment,when the laser power is 1.4 k W,scanning speeding is 0.48 mm/min,scanning interval is 2.2 mm,it has a relatively good production efficiency and wear-resisting performance.