This study investigates how the vibrational modes and bandgap of two-dimensional molybdenum disulfide (MoS₂) vary under different degrees of bending strain and with different atomically thin layer numbers, analyzing how layer parity governs the material's optical response. While strain engineering is pivotal for 2D materials, the evolution of vibrational modes across the transition from non-centrosymmetric (odd) to centrosymmetric (even) layers remains underexplored. Mechanically exfoliated 1~5-layer MoS₂ samples were transferred onto flexible PVC substrates and subjected to uniform uniaxial strain (0–2%) using a custom two-point bending system to induce stress and strain in the sample. Raman and Absorption spectroscopy quantified phonon mode splitting and exciton bandgap evolution to observe how the Raman shifts of various vibrational modes, as well as the exciton peak wavelength and absorption intensity, change with strain. Results reveal a striking layer-parity effect. In odd-numbered layers (1, 3, 5), the in-plane E2g1 (E′) mode split into distinct E+′ and E−′ branches, attributed to the breaking of x-y degeneracy in the non-centrosymmetric D3h point group. Conversely, even layers (D6h), possessing inversion symmetry, maintained mode degeneracy. Additionally, exciton red-shift rates exhibited a non-monotonic ""zigzag"" dependence on layer number, confirming strong modulation by spin-orbit coupling. This research reveals ""Layer-Parity Strain Engineering"" as a precise method for tuning optoelectronic properties, demonstrating that mechanical force can selectively break rotational symmetry to modulate bandgaps in flexible devices. It demonstrates the feasibility of using bending strain as a means to tune the physical properties of MoS₂ two-dimensional materials.