The　elastic　fibre　prestressing　(EFP)　technique　has　been　developed　to　balance　the　thermal　residual　stress　generated　during　curing　of　a　polymeric　composite.　The　continuous　fibre　reinforcements　are　prestressed　and　then　impregnated　into　a　polymeric　matrix,　where　the　prestress　load　is　only　removed　after　the　resin　is　fully　cured　in　order　to　produce　an　elastically　prestressed　polymeric　matrix　composite　(EPPMC).　Although　the　EFP　is　active　in　improving　the　static　mechanical　performance　of　a　composite,　its　mechanics　on　dynamic　mechanical　performance　and　viscoelasticity　of　a　composite　is　still　limited.　Here,　we　established　a　theoretical　model　in　order　to　decouple　the　EFP　principle,　aiming　to　better　analyse　the　underlying　mechanics.　A　bespoke　fibre　prestressing　rig　was　then　developed　to　apply　tension　on　a　unidirectional　carbon-fibre-reinforced　epoxy　prepreg　to　produce　EPPMC　samples　with　various　EFP　levels.　The　effects　of　EFP　were　then　investigated　by　carrying　out　both　static　and　dynamic　mechanical　testing,　as　well　as　the　viscoelastic　creep　performance.　It　was　found　that　there　is　an　optimal　level　of　EFP　in　order　to　maximise　the　prestress　benefits,　whilst　the　EFP　is　detrimental　to　the　fibre/matrix　interface.　The　EFP　mechanisms　are　then　proposed　based　on　these　observations　to　reveal　the　in-plane　stress　evolutions　within　a　polymeric　composite.　©　2023　by　the　authors.