Abstract: Taking TC4 alloy powder as raw material, TC4 alloy tensile samples were formed by electron beam selective melting technology. The effects of axial and radial forming directions and adding support on the microstructure and tensile properties of the alloy were studied. The results show that there were equiaxed β crystals and intragranular acicular α' phase in the radial formed alloy without support, forming Widmanstatten cluster structure and net basket structure; after adding support, it was composed of coarse β columnar crystal and net basket structure at two sides. The upper part of the axial formed alloy without and with support was composed of primary α phase and α' phase, while the lower part was equiaxed structure. The tensile properties of the radial formed alloy with support were significantly better than those of the radial formed alloy without support with average tensile strength of 1 173.52 MPa, the yield strength of 1 155.69 MPa, and the percentage elongation after fracture of 15.57%. The tensile properties of the axial formed alloy with support were comparable to those of the axial formed alloy without support, and were worse than those of radial formed alloy.