In order to systematically study the effect of laser irradiation on the interfacial bonding and compactness of SLD-Ti6Al4V coatings and to reveal the relationship between the interfacial bonding and wear resistance of coatings, the SLD-Ti6Al4V coatings were prepared on the Ti6Al4V substrate with different laser irradiation powers. The microstructures, phase compositions, micro-hardness and wear-resistant properties of these coatings were investigated by SEM, EDS, XRD,micro-hardness tester and wear tester. The results show that laser irradiation can induce in-situ nitriding reaction at the interface of particles in SLD-Ti6Al4V coatings to form titanium nitride ceramic phase, and the size and content of titanium nitride increase with the increase of laser irradiation power. When laser irradiation power is 800 W, the width of titanium nitride ceramic phase can reach 4.5 μm, and the area fraction of ceramic phase in the coatings can reach 28.06%. The porosity of SLD-Ti6Al4V coatings can be reduced from 8.28% to 1.85% due to the closing effect of relative pores of the titanium nitride ceramics at the interface. The micro-hardness of SLD-Ti6Al4V coatings can reach 360-370 HV due to the existence of hard ceramic phase. In addition, the SLD-Ti6Al4V coatings have better wear resistance than the Ti6Al4V substrate and CS-Ti6Al4V coatings. This is due to the in-situ formation of nitride reaction layers including Ti₂N and TiN at the particle interface under the synergistic effect of high-energy laser heating and high-pressure nitrogen gas source, which not only improves the compactness of the coatings, but also facilitates metallurgical bonding between particles, and thus improves the interfacial bonding strength. These in-situ formed and well-bonded titanium nitride ceramic phases significantly improve the wear resistance of SLD-Ti6Al4V coatings.