A　laser　clad　NiCrBSi　composite　coating　was　fabricated　on　the　surface　of　42CrMo　steel　using　6kW　fibre　laser.　The　morphology　and　composition　of　the　composite　coating　formed　under　different　powers　were　studied　using　scanning　electron　microscopy,　energy-dispersive　spectroscopy,　X-ray　diffraction　spectroscopy.　The　microhardness　and　wear　resistance　were　measured　with　a　MICROMET-5103　digital　microhardness　tester　and　a　MM-200　ring-block　wear　testing　machine,　respectively.　The　results　showed　that　the　cladding　layer　and　the　substrate　have　good　metallurgical　bonding.　The　microstructure　nearing　the　fusion　line　is　a　columnar　grain　and　that　of　the　cladding　layer　is　mainly　a　cellular　grain.　The　main　phases　of　the　laser　cladding　layer　are　gamma-Ni,　(Fe,Ni),　M7C3,　M23C6　and　CrB.　The　dilution　rate　of　the　laser　cladding　layer　increased　with　the　increase　of　laser　power.　The　microhardness　of　the　cladding　layers　decreased　with　the　increase　of　laser　power,　and　wear　resistance　of　the　cladding　layer　first　increased　and　then　decreased　with　the　increase　of　laser　power.　When　the　laser　power　was　2000W,　the　wear　resistance　of　the　composite　coating　was　at　its　highest.