Abstract：Selective laser melting (SLM) additive manufacturing technology is commonly used in the manufacture of complex small parts in the fields of aviation, aerospace and weapons, such as grille, cavity structure, combustion chamber components, etc. In order to adapt to the manufacturing of large-size parts, the ideal scheme is to adopt segmented additive forming and tailor welded joint. In this paper, the electron beam welding (EBW) process of SLM formed TC4 titanium alloy is verified, the welding porosity defects and their reasons are analyzed, and the improvement effect of different welding processes on the porosity defects is discussed. After the process optimization, the number and distribution of porosities are analyzed. The results show that the number and size of porosities are greatly reduced, the quality of electron beam welding meets the requirements of HB/Z 198 for level I standard, and the joint shows good tensile and fatigue properties at room temperature. Through the analysis and research, the feasibility of the hybrid manufacturing technology of SLM and EBW in the field for aviation manufacturing is verified.