The weldability of in-situ titanium matrix composites (TMCs) was studied using the gas tungsten arc welding (GTAW). The effects of GTAW on the microstructure of fusion zone and heat-affected zone were discussed, and the changes of TiB whisker reinforcements in the welded joint were investigated by optical microscope (OM), scanning electron microscopy (SEM), XRD analysis and tension testing at room temperature. Research results show that the GTAW process is a suitable welding method for in-situ TMCs. Under reasonable welding parameters, the welded joints display goo weld seam formation, and TiB whiskers show distinctly smaller sizes and uniform distribution with a special network structure. The maximum tensile strength of welded joints can reach 92% of the base metal under optimum welding parameters.