Thermal　residual　stress　generated　during　curing　is　known　to　be　detrimental　to　mechanical　performance　of　a　fibre　reinforced　composite.　Elastic　fibre　prestressing　has　been　developed　to　reduce　the　negative　effects　induced　by　the　curing　generated　thermal　residual　stress,　but　the　acting　mechanisms　of　prestrain　on　dynamic　interfacial　strengthening　within　the　composite　is　still　unknown.　In　this　paper,　a　bespoke　fibre　prestressing　device　was　developed　to　apply　biaxial　stretching　to　a　plain-weave　carbon　fibre　reinforced　epoxy　prepreg　with　different　prestrain　levels.　The　effects　of　prestrain　were　then　investigated　by　carrying　out　dynamic　thermomechanical　analysis.　It　is　found　that　fibre　prestraining　is　able　to　improve　the　fibre-matrix　interface　strength,　and　there　is　an　optimal　prestrain　level　to　maximise　the　prestrain　benefits.　The　prestrain　mechanisms　are　then　presented　based　on　these　observations.　The　prestrain　composite　can　effectively　improve　its　negative　impact　due　to　thermal　residual　stress,　thereby　improving　its　industrial　applications.