The work aims to improve the tribological properties of titanium and titanium alloys in space environments and expand the application range of titanium and titanium alloy in space technology. NiCrBSi/Ag composite coating was prepared on pure titanium substrate by laser cladding technology. The phase composition, microstructure and crystal structure of the coating were analyzed by X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy. The tribological properties of NiCrBSi/Ag composite coating under high vacuum, atomic oxygen and ultraviolet irradiation in simulated space environment and atmospheric environment were studied by space tribology experiment system. The wear marks of NiCrBSi/Ag composite coating and the antithesis stainless steel ball were analyzed by SEM and EDS. The wear mechanism of NiCrBSi/Ag composite coatings in three simulated space and atmospheric environments was investigated. The main phases of NiCrBSi/Ag composite coating prepared by laser cladding on the surface of pure titanium substrate were NiTi, Ni3Ti, Cr2Ni3, Cr3Si, TiB2, Cr-Ni-Ti-Fe and Ag. The microstructure of composite coating was mainly composed of equiaxed crystal and dendritic crystal. The composite coating had high microhardness and the average microhardness of coating section was about 830 HV0.2, which was about 4.4 times of that of titanium substrate. The friction coefficient and wear rate of the composite coating under high vacuum, atomic oxygen and ultraviolet radiation were smaller than those under atmospheric environment. The wear rate of composite coating in three simulated space environments was about 2 orders of magnitude smaller than that of pure titanium substrate. The wear mechanism of composite coating under high vacuum, atomic oxygen and ultraviolet radiation was adhesive wear and abrasive wear, while the wear mechanism in atmospheric environment was abrasive wear. NiCrBSi/Ag composite coating can significantly improve the tribological properties of pure titanium substrate under high vacuum, atomic oxygen and ultraviolet irradiation space environments.