A　novel　metastable　(3　titanium　alloy　Ti-4Mo-3V-4Cr-0.5Fe-3.5Al-0.3　O　was　conducted　heat　treatment,　achieving　a　remarkable　balance　of　mechanical　properties.　The　heat　treatment　condition　labeled　HT6　yields　an　optimal　combination　of　strength　(1508　MPa)　and　ductility　(8.7　%　elongation).　Microstructural　analyses　reveal　that　the　size　and　distribution　of　both　alpha　p　phases　and　alpha　s　phases　in　HT6　are　most　conducive　to　enhancing　the　comprehensive　mechanical　properties.　Microstructural　characterization　highlights　the　retention　of　a　appropriate　alpha　p　phase　distribution　(26/100　mu　m2,　0.78　mu　m　size)　after　a　low-temperature,　long-duration　solution　treatment,　coupled　with　the　subsequent　generation　of　alpha　s　precipitates　featuring　advantageous　morphologies　(1.1　aspect　ratio,　0.185　mu　m　spacing)　through　a　low-temperature,　long-duration　aging　treatment.　Fractographic　assessments　of　HT6　illustrate　a　homogeneous　distribution　of　ductile　dimples　across　fiber　zones,　devoid　of　cleavage　facets,　indicative　of　its　ductile　response,　whereas　lateral　fractures　display　cleavage　features,　testament　to　the　alloy＇s　strength-ductility　balance.　Grain　structure　analysis　underscores　a　well-balanced　crystallographic　orientation　diversity　and　strategic　positioning　of　large-angle　grain　boundaries,　collectively　impeding　dislocation　disorder　and　promoting　orderly　glide　mechanisms,　thereby　unifying　high　strength　with　substantial　ductility.　In　HT6,　the　alpha　p　phase　contains　a　large　number　of　dislocations　that　do　not　form　tangles,　with　a　moderate　grain　orientation　that　helps　balance　dislocation　slip　and　hindrance,　allowing　dislocations　to　effectively　slip　during　plastic　deformation　without　causing　a　decrease　in　ductility.　The　high　density　of　dislocations　in　the　(3　matrix　indicates　significant　plastic　deformation;　however,　due　to　the　moderate　grain　orientation,　dislocations　can　effectively　reorganize　or　be　stored,　avoiding　a　reduction　in　ductility.　The　alpha　s　phase　exists　in　a　triangular　interlocking　form　with　complex　orientations,　effectively　impeding　dislocation　slip,　which　further　increases　the　alloy＇s　strength.　These　synergistic　microstructural　features　and　mechanical　behaviors　contribute　to　the　unique　and　superior　strength-ductility　synergy　of　the　HT6　alloy.　This　study　dissects　the　microstructural　mechanisms　governing　the　synergistic　enhancement　of　strength　and　ductility　in　Ti-4Mo-3V-4Cr-0.5Fe-3.5Al-0.3　O,　emphasizing　the　pivotal　influence　of　heat　treatment　controling　on　alloy　microarchitecture　and　properties,　furnishes　a　foundational　understanding　and　pragmatic　roadmap　for　the　advancement　of　titanium　alloys.