The microstructure and mechanical properties of Ti-6Al-4V repaired by laser additive manufacturing were studied, and the effect of the build orientation on additive zone microstructure, microhardness, tensile properties and fracture morphologies of Ti-6Al-4V were investigated. Results show that a typical basketweave microstructure is featured in the additive zone, of which the fine basketweave microstructure is obtained in the additive height direction, and the basketweave microstructure including the equiaxed α phase is obtained in the tile direction. There are plenty of elongated α lath and a few acicular α′ in the scanning direction, due to the less heat accumulation, rapid heat dissipation, and its proximity to the junction zone. The microhardness is approximately 345 HV in the scanning direction, which is increased by 4.1% compared to that in the height and tilt direction for the additive zone. For the junction zone, the microhardness is the highest in the scanning direction, which can reach 362 HV. The room-temperature tensile properties show obvious anisotropy for different orientations. The highest tensile strength is exhibited in the scanning direction, while the plasticity is slightly reduced. On the contrary, the property with lower tensile strength and higher plasticity is exhibited in the height and tilt direction, and the fracture morphology is characterized by ductile fracture for different orientations.