4,4'-(Phenylimino)dibenzaldehyde (PIDB), exhibits excellent photoelectronic properties and holds significant promise for applications in functional dyes, photovoltaic devices, and biosensing. This study systematically investigates the excited-state dynamics of PIDB by integrating time-dependent density functional theory (TD-DFT) calculations with femtosecond time-resolved transient absorption spectroscopy. Theoretical computations were performed using the Gaussian software package at the B3LYP/6-31G(d) level, incorporating the IEFPCM solvation model for molecular structure optimization and excited-state energy calculations. The results reveal that upon excitation to the S₁ state, PIDB undergoes a pronounced intramolecular charge transfer (ICT) process, characterized by the directional transfer of electron density from the triphenylamine donor skeleton to the formyl acceptor groups. To elucidate the underlying dynamical evolution pathways, femtosecond transient absorption spectroscopy experiments were further conducted to systematically probe the ultrafast excited-state dynamics of PIDB in methanol (MeOH) and ethylene glycol (EG). Global fitting of the transient absorption spectra yielded species-associated difference spectra (SADS), confirming that the excited-state evolution comprises three characteristic kinetic components. Kinetic analysis indicates that following 380 nm pump excitation, PIDB is initially populated into the localized excitation (LE) state and rapidly relaxes to the ICT-characterized S₁ state within the instrument response time (0.2 ps). Subsequently, the molecule undergoes further relaxation to the ICT' state via structural twisting on a 4.7 ps timescale. This structural twisting process exhibits a marked dependence on solvent viscosity, with the relaxation rate decreasing as viscosity increases; specifically, the twisting relaxation time extends to 15.7 ps in more viscous EG. Ultimately, the population in the ICT' state decays back to the ground state via internal conversion with time constants of 31.8 ps in MeOH and 48.2 ps in EG. The findings demonstrate that elevated solvent viscosity enhances intermolecular interactions and steric hindrance, thereby suppressing large-amplitude structural twisting of the excited state, reducing the relaxation rate, and prolonging the structural twisting time. This work clarifies the solvent effects and structural twisting dynamics governing the excited-state relaxation of PIDB on an ultrafast timescale, providing crucial theoretical and experimental insights for the molecular design, performance optimization, and photoelectric modulation of triphenylamine-based photo-functional molecules.