The microstructure and mechanical property of forming parts by electron beam selective melting (EBSM) for ELI Ti-5Al-2.5Sn metal powder were investigated by means of optical microstructure and SEM, and universal mechanical testing machine. The results indicate that the density, the elongation and the room temperature strength of the forming parts are improved effectively according to zigzag scanning way with a vacuum of 3.0×10-2 to 5.0×10-2 Pa and a current of 2.0 to 3.0 mA,. The relative density, the tensile strength and the elongation are 97%, 740 MPa and 8%, respectively, close to the properties of forging parts, due to the transit liquid phase from the electron beam high energy utilization during sintering. Meanwhile, the cleaned surfaces of powders in vacuum improve the sintering actively. A rapid condensation process makes forming fine grains easy, while the increase of density and the refinement of grains are helpful to improve the mechanical properties of parts.