An excitonic insulating phase is predicted in narrow gapped semiconductors and semimetals, where electrons and holes driven by Coulomb interaction may sustain spontaneous condensation. The identification of the excitonic insulator state is challenging for the coexistence of a structural phase transition with the same symmetry breaking. Ta2NiSe5, being the most promising excitonic insulator candidate, is obscure to identify between an electronic origin of such phase transition, or a phonon driven scenario. Here we carried out electronic transport measurement under uniaxial strain applied by a piezo-based strain device, and Raman Scattering to study the strain-tuned behavior of the critical fluctuation as a quasi-elastic scattering in B2g symmetry, which could provide missing information on the relation of excitonic condensation and lattice dynamics.