Abstract: The high-power fiber laser "keyhole" welding and high-pressure electron beam welding processes were studied by using 10 mm thick TA5 titanium alloy. The results show that both laser and electron beam welding can produce well-formed "keyhole" joints, with electron beam welding offering a higher energy density. Both processes achieve smooth surface formation on the front of the weld, but laser welding produces a superior backside formation. Both processes result in high energy beam weld cross-sections with a high aspect ratio greater than 2 ∶1, with electron beam welding having an even larger aspect ratio. The laser weld bead exhibits a typical "neck" morphology, while the electron beam weld bead presents a typical "I" shape. The simulation results using ABAQUS confirm the differences in weld cross-sectional morphology between the two processes. Both weld zones show distinct columnar grain structures, with the original β columnar grains growing in a typical competitive manner. The weld zone mainly exhibits a typical α-type titanium alloy weld morphology, characterized by serrated α-mixed and spot β phases. X-ray and penetrant tests on the welds for both processes meet the non-destructive testing standards. The tensile strength of the laser and electron beam welded joints reaches over 800 MPa and 700MPa, respectively, and both processes satisfy the bending test standards. The hardness testing shows a slight increase in hardness in the weld zone, but the values fully meet the standard requirements for titanium alloy welded joints’ hardness variation.