A　bistable　composite　cylindrical　shell　is　a　thin-walled　structure　that　can　change　shape　between　two　stable　configurations　under　small　energy　input,　showing　great　potential　to　be　applied　to　space　deployable　mechanics.　The　internal　stress　level　within　a　cylindrical　shell　plays　a　vital　role　in　determining　its　morphing　mechanics,　whilst　tailoring　the　internal　stress　is　tricky　for　traditional　composite　manufacturing　methods.　In　this　paper,　we　devise　a　novel　biaxial　elastic　fibre　prestressing　(EFP)　method　to　systematic　design　and　produce　prestrained　carbon-based　composite　cylindrical　shells,　with　tailorable　bistability　and　morphing　mechanics,　as　well　as　improved　loadcarrying　capabilities.　A　biaxial　fibre　stretching　rig　was　devised　to　apply　tensions　on　both　directions　of　a　plainweave　carbon　prepreg　simultaneously;　prestrained　cylindrical　shell　samples　were　produced　with　various　prestrain　levels　to　fully　evaluate　the　fibre　prestraining　effects;　a　finite　element　model　was　established　and　showed　good　agreement　with　experimental　observations.　The　fibre　prestraining　mechanisms　were　then　proposed.　It　is　found　that　EFP　is　effective　in　tailoring　the　internal　strain/stress　level　within　a　composite　cylindrical　shell,　which　in　turn　altering　the　structural　morphing　mechanics,　and　able　to　significantly　lower　the　maximum　tensile　strain　during　shape-changing,　thus　improve　the　load-carrying　capability.　These　findings　are　expected　to　facilitate　structural　design　of　the　deployable　composite　structures　and　flexible　mechanical　hinges,　by　allowing　further　design　freedoms　in　terms　of　morphing　mechanics　and　load-carrying　capability.