Laser shock processing (LSP) is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. This process induces intensive plastic deformation and deeper compressive residual stress and improves the surface performance of materials. The titanium alloy of TC4-DT is the important materials in many industry fields including aviation, which is used widely on hole and welding structure. However, the researches of surface treatment on TC4-DT welding structure using LSP technology are seldom reported by now. The performances of TC4-DT, including mircrohardness and surface profiles, are improved through the technology of LSP.