This study investigates the effect of uniaxial strain on graphene using Raman spectroscopy and first-principle calculations. Graphene was deposited on a transparent, flexible substrate (polyethylene terephthalate, PET) and uniaxial tensile strain up to ~0.8% was applied by stretching the PET in one direction. Raman spectroscopy revealed significant redshifts in the 2D and G bands of single-layer graphene, with shifts of -27.8 cm⁻¹ and -14.2 cm⁻¹ per 1% strain, respectively. These shifts are attributed to the elongation of carbon-carbon bonds, indicating successful application of uniaxial strain on graphene. First-principle calculations predicted a bandgap opening of ~300 meV for graphene under 1% uniaxial tensile strain, suggesting that uniaxial strain can be used to tune the bandgap of graphene more efficiently and controllably than other methods. The flexible substrate is suitable for such strain processes, and Raman spectroscopy can serve as an ultra-sensitive method to determine strain. The study also shows that uniaxial strain can break the sublattice symmetry of graphene, leading to a bandgap opening at the K point. The results demonstrate that uniaxial strain can significantly affect the electronic and optical properties of graphene, and that the strain is reversible and recoverable. The study provides an alternative method for fabricating graphene-based devices by applying uniaxial strain. The findings suggest that uniaxial strain on graphene can be easily realized by stretching the flexible substrate and that the resulting bandgap is more efficient and controllable than other methods. The study also highlights the potential of graphene as an ultrasensitive strain sensor. The results are supported by experimental data and first-principle calculations, and the study provides a comprehensive understanding of the effect of uniaxial strain on graphene.This study investigates the effect of uniaxial strain on graphene using Raman spectroscopy and first-principle calculations. Graphene was deposited on a transparent, flexible substrate (polyethylene terephthalate, PET) and uniaxial tensile strain up to ~0.8% was applied by stretching the PET in one direction. Raman spectroscopy revealed significant redshifts in the 2D and G bands of single-layer graphene, with shifts of -27.8 cm⁻¹ and -14.2 cm⁻¹ per 1% strain, respectively. These shifts are attributed to the elongation of carbon-carbon bonds, indicating successful application of uniaxial strain on graphene. First-principle calculations predicted a bandgap opening of ~300 meV for graphene under 1% uniaxial tensile strain, suggesting that uniaxial strain can be used to tune the bandgap of graphene more efficiently and controllably than other methods. The flexible substrate is suitable for such strain processes, and Raman spectroscopy can serve as an ultra-sensitive method to determine strain. The study also shows that uniaxial strain can break the sublattice symmetry of graphene, leading to a bandgap opening at the K point. The results demonstrate that uniaxial strain can significantly affect the electronic and optical properties of graphene, and that the strain is reversible and recoverable. The study provides an alternative method for fabricating graphene-based devices by applying uniaxial strain. The findings suggest that uniaxial strain on graphene can be easily realized by stretching the flexible substrate and that the resulting bandgap is more efficient and controllable than other methods. The study also highlights the potential of graphene as an ultrasensitive strain sensor. The results are supported by experimental data and first-principle calculations, and the study provides a comprehensive understanding of the effect of uniaxial strain on graphene.