To evaluate the potential of phase-change materials (PCMs) in improving the indoor thermal and airflow environment of Trombe walls under solar energy limitations, a computational fluid dynamics (CFDs) model was employed in this study to perform comparative simulations. Taking traditional Trombe walls (TWs) as the control group and PCM-Trombe walls (PCM-TWs) as the experimental group, the simulation analysis was carried out based on meteorological data from a typical spring day in Hangzhou in 2024. The results indicate that the application of PCM significantly reduced temperature fluctuations in the air channel, lowering the peak temperature by 8.3 °C. Meanwhile, it delayed the decline in ventilation rate, extending the effective ventilation time by approximately one hour. Moreover, by calculating the Grashof number and ventilation rate, it was observed that the buoyancy effect of PCM-TWs is weaker than that of TWs at the peak wind speed, resulting in a lower natural convection intensity. The ventilation rate variation trend of PCM-TWs was smoother, with its peak ventilation rate slightly lower than that of TWs by 0.008 kg/s.