To investigate the effect of asymmetric bulky substitution at the dual α-positions on the excitedstate dynamics, bromotriphenylethylene was selected as the model compound, which is structurally characterized by the introduction of a phenyl ring and a bromine atom at the two α-positions of stilbene. Femtosecond transient absorption spectroscopy combined with quantum chemical calculations was employed to systematically investigate the excited-state dynamics of this molecule in acetonitrile and n-hexane solutions. The experimental results revealed that upon 320 nm photoexcitation to the S₁ state, the transient absorption spectra exhibited a rapid blue-shift feature, and the relaxation process followed a three-step pathway: "Franck-Condon state (acetonitrile: 0.13 ps; n-hexane: 0.16 ps) → FC relaxed state (acetonitrile: 0.41 ps; n-hexane: 0.3 ps) → twisted state (acetonitrile: 46 ps; n-hexane: 16.5 ps)." Further investigation indicated that solvent polarity significantly influences the lifetimes of the twisted state: τ₃ was notably prolonged in polar acetonitrile but shorter in nonpolar n-hexane. Due to the electron-withdrawing effect of the bromine atom, the twisted state owns a larger dipole moment, thereby it is likely to be stabilized by polar solvents. In contrast, the first two relaxation steps are not sensitive to solvent polarity. This study elucidates the special role of asymmetric bulky substitution on the relaxation pathway of stilbene derivatives and highlights the critical influence of solvent polarity, providing new insights for the rational design of photoswitchable molecular systems.