Introduction:　Long　bone　fracture　is　common　in　traumatic　osteopathic　patients.　Good　reduction　is　beneficial　for　bone　healing,　preventing　the　complications　such　as　delayed　union,　nonunion,　malunion,　but　is　hard　to　achieve.　Repeated　attempts　during　the　surgery　would　increase　the　operation　time,　cause　new　damage　to　the　fracture　site　and　excessive　exposure　to　radiation.　Robotic　and　navigation　techniques　can　help　improve　the　reduction　accuracy,　however,　the　high　cost　and　complexity　of　operation　have　limited　their　clinical　application.　Materials　and　methods:　We　combined　3D　printing　with　computer-assisted　reduction　technique　to　develop　a　customised　external　fixator　with　the　function　of　fracture　reduction.　The　original　CT　data　obtained　by　scanning　the　fracture　was　imported　to　computer　for　reconstructing　and　reducing　the　3D　image　of　the　fracture,　based　on　which　the　external　fixator　(named　as　Q-Fixator)　was　designed　and　then　fabricated　by　3D　printing　techniques.　The　fracture　reduction　and　fixation　was　achieved　by　connecting　the　pins　inserted　in　the　bones　with　the　customised　Q-Fixator.　Experiments　were　conducted　on　three　fracture　models　to　demonstrate　the　reduction　results.　Results:　Good　reduction　results　were　obtained　on　all　three　fractured　bone　models,　with　an　average　rotation　of　1.21　degrees(+/-　0.24),　angulation　of　1.84　degrees(+/-　0.28),　and　lateral　displacement　of　2.22　mm(+/-　0.62).　Conclusions:　A　novel　customised　external　fixator　for　long　bone　fracture　reduction　was　readily　developed　using　3D　printing　technique.　The　customised　external　fixator　had　the　advantages　of　easy　manipulation,　accurate　reduction,　minimally　invasion　and　experience-independence.　Future　application　of　the　customised　external　fixator　can　be　extended　to　include　the　fixation　function　with　stress　adjustment　and　potentially　optimise　the　fracture　healing　process.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.