To increase the mechanical properties of the metal rollers, Mo and Mo+Y2O3 alloy powders were designed. And a kind of coating fabricated by a continuous wave CO2 laser surface alloying(LSA) on 40Cr steel roller was obtained. The effect of Mo and Mo+Y2O3 on microstructure, hardness and wearing resistance of alloying coating were studied by OM, SEM, XRD, microhardness tester and wearing tester. The experimental results indicate that the grain size in alloying coating is obviously fined, and the grain boundary is strengthened. The uniformity and density of microstructure are improved. The microhardness and wear resistance of alloying coating are significantly increased.