Abstract Vacuum electron beam brazing experiments of pure titanium TA2 with automated feeding AgCu28 wire as filler metal were carried out. The beam current and the welding speed could affect the welding heat inputs to affect the surface appearances, the microstructures and the tensile strengths of the brazed welds. The typical chemical microstructures of the brazed welds were composed of Ag-based solid solution, Ti2Cu and TiCu, meanwhile, α-Ti would exist at the interface under the higher beam current. Moreover, the higher welding speed would promote the loss of Ag-based solid solution. Both the uniform distribution of granular Ag-based solid solution and the existence of α-Ti phase could improve the tensile strength of the brazed joint. It implied that the new electron beam gun designed for space welding was dependable for brazing in the open space. It provides experience for the connection of titanium and titanium alloys in the space and provides the theoretical and experimental basis for its application in the space industry.