Laser　direct　melting　deposited　(LDMD)　Ti-6Al-4V　alloys　are　mainly　used　in　aerospace　fields.　It　is　very　important　to　study　their　deformation　behavior　as　a　function　of　the　application　conditions　(i.　e.　temperature　and　stress).　This　work　compared　the　dynamic　microstructure　evolution　and　mechanical　properties　of　LDMD　Ti-6Al-4V　alloys　at　23　degrees　C　and　650　degrees　C.　A　method　based　on　in-situ　scanning　electron　microscopy　(SEM)　tensile　testing　was　used　to　identify　the　initiation　of　cracks　and　propagation　mode　of　slip　bands.　The　deformation　mechanisms　at　low　and　elevated　temperatures　were　discussed.　The　results　showed　that　the　strength　decreased　and　the　elongation　increased　with　increasing　temperature.　These　results　were　verified　by　the　propagation　modes　of　slip　bands　and　opening　of　the　active　deformation　systems.