The　WC-Ni　base　superhard　composite　tungsten　carbide　coatings　were　fabricated　by　wide-band　laser　cladding　technique　on　45　steel.　The　morphology　of　laser　clad　layer　was　observed　by　scanning　electronic　microscope(SEM)　,　the　composition　analysis　was　applied　by　EDS,　and　the　phase　transformation　was　characterized　by　XRD.　The　microstructure,　hardness,　and　distribution　of　two　types　of　laser　clad　coatings　were　contrastively　investigated,　including　single　cladding　coating　and　gradient　cladding　coating.　The　results　show　that　single　cladding　coating　usually　has　cracks　existing　in　the　interface　area,　and　the　inferior　in　interface　bind.　In　the　gradient　cladding　coating,　stress　concentration　is　released　through　step-by-step　transition　and　distributed　properly.　Under　optimized　processing　parameters,　the　gradient　structure　can　be　realized　by　sequential　controlling　raicrostructural　elements.　The　gradient　cladding　coating　is　free　of　pores　and　cracks.　Thereinto,　the　main　structure　of　gradient　cladding　coating　is　composed　of　the　phase　of　γ-Ni,　WC　etc.　The　trend　of　hardness　distribution　is　gradually　decreased　from　the　coat　to　the　substrate.　The　average　hardness　of　the　outer　layer　is　above　2000　HV0.1.