Laser　cladding　Ni-based　composite　coating　was　fabricated　on　the　surface　of　42CrMo　steel　using　6　kW　fibre　laser.　By　the　addition　of　Mo　powder,　a　well-formed　and　crack-free　laser　cladding　composite　coating　was　obtained.　The　morphology,　composition,　microhardness　and　wear　resistance　of　composite　coatings　were　studied　using　a　scanning　electron　microscopy,　an　energy-dispersive　spectroscopy,　an　X-ray　diffraction　spectrum,　a　microhardness　tester　and　a　wear　tester.　The　results　show　that　the　cladding　layer　has　metallurgical　bonding　with　the　substrate.　The　main　phases　of　Ni45+10%Mo　laser　cladding　layer　are　(Fe,　Ni),　Cr23C6,　Cr3C2,　Mo2FeB2　and　Cr2B3.　After　the　addition　of　Mo　powder,　the　size　of　the　microstructure　of　composite　coatings　is　finer　than　that　of　Ni45　cladding　layer.　Stubby-rod　carbides　are　displayed　in　the　interdendritic　interface.　The　molybdenum　and　chromium　are　rich　in　the　grain　boundaries.　The　distribution　of　hardness　is　uniform　in　Ni-based　cladding　layer,　and　its　microhardness　is　significantly　higher　than　that　of　the　substrate.　Ni45+10%Mo　composite　coating　has　the　best　wear　resistance.　Its　wear　resistance　reaches　1.734　times　of　Ni45　coating　and　2.367　times　of　42CrMo　steel.