High　power　diode　laser　(HPDL)　is　advanced　portable　equipment　with　the　high　value　electrical　to　optical　conversion　efficiency.　Diode　lasers　have　seen　wide　applications　in　material　fabrication　and　processing.　Aggregate　WC-Ni　based　superhard　composites　were　fabricated　on　304　stainless　steel　substrate.　Wear-resistant　coatings　were　fabricated　by　a　3　kW　diode　laser　with　direct　injection　powders　into　the　molten　pool.　The　coating　had　excellent　bonding　with　the　substrate　and　was　free　of　pores　and　cracks.　The　morphology　of　laser　cladding　layer　was　observed　by　scanning　electronics　microscope　(SEM),　composition　analysis　was　applied　by　energy　dispersive　spectroscopy　(EDS),　and　the　phase　transformation　was　characterized　by　X-ray　diffraction　(XRD).　The　results　showed　that　WC-Ni　based　superhard　composites　was　fabricated　by　high　power　diode　laser　with　high　content　tungsten　carbide　(60%)　and　low　dilution.　The　main　structure　of　diode　laser　cladding　WC-Ni　based　alloy　was　γ-Ni,　WC,　W2C,　Ni3B,　CrB2　etc.　The　hardness　of　the　laser　clad　layer　is　inhomogeneously　distributed　with　the　average　value　of　HV　1100,　higher　than　the　substrate　of　HV　350.　The　hardness　in　the　transition　region　is　gradient　distributed　with　steep　reduction.