Pre-alloyed Ti6Al4V powder was used to fabricate solid components by Electron Beam Selective Melting (EBSM). The characteristics of microstructures of the powder were investigated using OM, SEM, TEM and XRD. Results show that the EBSMed Ti6Al4V alloy contains fine-acicular martensite, basket-weave (α+β) as well as widmanstatten (α+β), and the martensite mainly concentrates at the last dozens of forming layers. With the increase of P/V, the height of martensite region rises from 7~8 forming layers to 22~25 forming layers. In addition, the mixed internal microstructure of basket-weave and widmanstatten is formed instead of lamellar widmanstatten microstructure. Meanwhile, the thickness of lamellar α phase increases from 1~2 μm to 2~4 μm