To establish a visualized correlation between the micro- and meso-scale structures of hydroxyl-terminated polybutadiene (HTPB)-based polyurethane elastomers for crack detection, a dihydroxy-functionalized europium complex Eu(TTA)?DMPA was synthesized using 2-thenoyltrifluoroacetone (HTTA) and 2,2-bis(hydroxymethyl)propionic acid (DMPA) as ligands with trivalent europium ions (Eu3?) as the central metal. This complex was incorporated as a chain extender via covalent bonding during the hard segment synthesis of HTPB-based polyurethane elastomers, resulting in a elastomer (E-HTPB-PU) prepared through fluorescence labeling. The structural composition and fluorescence properties of Eu(TTA)?DMPA and E-HTPB-PU were characterized using FTIR and fluorescence spectroscopy. The effects of hard segment content (composed of [Eu(TTA)?DMPA and 1,4-butanediol (BDO)]) on mechanical properties and the fluorescence intensity-strain relationship during visualized tensile deformation were investigated through tensile testing and Abaqus simulation. Results demonstrated that the chemical formula of Eu(TTA)?DMPA was determined as Eu(C?H?O?SF?)?C?H?O?. The E-HTPB-PU exhibited tunable fluorescence intensity with optimal comprehensive mechanical properties at 15% hard segment content (E-HTPB-PU-15%), demonstrating a tensile strength of 1.212 MPa and elongation at break of 1074%. An inverse correlation was observed between tensile strain and fluorescence intensity in E-HTPB-PU, where increased deformation led to reduced fluorescence intensity, establishing a visualized correspondence between mechanical and chemical signals during tensile strain. Notably, microcrack formation during stretching induced molecular chain breakage or slippage, causing localized Eu aggregation near cracks. This phenomenon resulted in enhanced fluorescence intensity at fracture regions despite the overall intensity reduction during deformation.