Correlation　between　tensile　strength　and　hardness　for　damage-tolerant　Ti-6Al-4V　(TC4-DT)　alloy　and　its　electron　beam　welded　joints　was　investigated.　Yield　strength　(YS),　ultimate　tensile　strength　(UTS)　and　strain　hardening　coefficient　of　base　metal　and　weld　metal　were　obtained　using　uniaxial　tensile　tests.　Microhardness　of　the　base　metal,　heat　affected　zone,　and　weld　metal　was　measured.　Then,　the　linear　correlations　among　the　yield　strength,　tensile　strength,　and　hardness　were　proposed.　Moreover,　correlation　between　strain　hardening　coefficient　and　the　ratio　of　YS　to　UTS　(YS/UTS)　was　established.　The　results　indicate　that　microhardness　can　be　used　to　predict　the　YS　and　UTS　of　the　TC4-DT　welded　joint　successfully.　In　addition,　the　strain　hardening　coefficient　can　be　predicted　by　the　YS/UTS.　The　prediction　of　strength　and　strain　hardening　coefficient　is　in　agreement　with　the　experiments.　The　correlations　are　applicable　and　valuable　for　the　strength　prediction　of　narrow　welded　fusion　zone　and　heat　affected　zone　based　on　the　microhardness　measurement.