A　large　number　of　hard　and　brittle　needle⁃like　α′　phases　are　presented　in　the　microstructure　of　TC4　alloys　fabricated　by　selective　laser　melting　(SLM)　due　to　the　extremely　fast　cooling　rates,　resulting　in　a　significant　decrease　in　the　plasticity　of　SLM　TC4　alloys,　which　seriously　limits　their　engineering　applications.　To　improve　the　plasticity　of　the　SLM　TC4　alloys,　the　effect　of　different　heat　treatment　temperatures　on　microstructure　and　mechanical　properties　of　SLM　TC4　alloys　was　systematically　investigated.　Results　show　that　the　needle⁃like　α′　phase　in　the　primary　β　grains　is　transformed　into　the　α　phase　after　heat　treatments　at　four　temperatures.　With　the　heat　treatment　temperature　increasing　from　860　℃　to　950　℃,　the　morphology　of　the　needle⁃like　α　phases　is　transformed　from　basket⁃like　distribution　into　a　colony　with　the　same　orientation.　Furthermore,　the　grain　size　of　α　phases　increases　from　1.　73　μm　to　2.　32　μm　and　the　fraction　of　β　phases　increases　from　0.　4%　to　2.　7%　.　The　ultimate　tensile　strength　(UTS)　of　SLM　TC4　alloys　is　slightly　reduced　from　961　MPa　to　870　MPa　while　the　elongation　index　(EI)　of　the　SLM　TC4　alloys　first　increases　and　then　is　reduced.　Among　the　temperatures,　the　UTS　of　941　MPa　and　the　EI　of　11.　1%　are　obtained　by　heat　treatment　at　890　℃,　which　increases　by　126.　5%　compared　with　the　unheat⁃treated　samples.　©　2023　Beijing　University　of　Technology.　All　rights　reserved.