For　electron　beam　welding　(EBW)　of　TC4　titanium　alloy　with　different　preheat　treatments　and　post-weld　heat　treatment,　microstructure　and　phase　composition　characteristics　of　these　welds　of　TC4　were　studied　by　means　of　optical　microscope　and　X-ray　diffraction.　Tension　and　impact　test　were　carried　out　at　room　temperature.　The　results　indicated　that　the　microstructure　of　two　kinds　of　base　metals　is　the　mixture　of　α　phase　and　β　phase,　but　their　state　and　distribution　are　different.　The　post-weld　solution　and　aged　operation　carried　out　in　the　case　of　annealed　welds　leads　to　a　coarsening　and　homogenous　of　the　acicular　α,　the　microstructures　is　typically　reticular　structure.　The　welds　in　solid　solution　state　were　given　a　relief　annealed　after　welding,　whose　microstructure　at　FZ　is　tempered　martensite　α　in　side　prior　β　grains　and　at　grain　boundary　α.　It　induced　that　the　ultimate　tensile　strength　(UTS)　of　annealed　state　welds　is　less　than　that　of　solution　treated　welds,　but　the　impact　toughness　of　the　former　is　greater　than　that　of　the　latter.　However,　the　UTS　and　impact　toughness　of　these　two　kinds　of　welds　are　greater　that　that　of　base　metal.