This article present our; experimental procedure in earbo-nitro-borconizing of 45# steel surface by usingahigh power CW CO2 laser. It also presents a comprehensive analysis of tbe phase structure, phase morpeology, distribution profile of teh three elements,thehardness and the resistance to abrasion of the sample. The experimental results indicate that the laser surface alloying of carbon, nttrogen and boron will give rise to many strengthening effects on the base metal.