<p>Pressure transients generated by two trains passing each other within an enclosed noise barrier can induce fatigue loads, cause damage to the noise barrier structures, and pose safety risks to high-speed trains. This study numerically investigated the influence of vents on pressure transients when high-speed trains pass each other at 350 km/h within an enclosed noise barrier, focusing on the vent cross-sectional area and number. Numerical simulations were conducted utilizing the Renormalization Group (RNG) k-ε turbulence model with a dynamic mesh method, and these simulations were validated against full-scale experimental results. The results indicated that vents alter the pressure waveform and significantly reduced the peak pressures induced by train intersections in the enclosed noise barrier. For a single vent, the optimal cross-sectional area ratio between the vent and the noise barrier was determined to be 0.24, achieving a 53.3 % reduction in peak-to-peak pressure. Introducing additional vents at the midpoints of the regions [<i>ML</i>/(1+<i>M</i>), (<i>L-L</i>_tr)/2] and [(<i>L+L</i>_tr]/2, <i>L</i>/(1+<i>M</i>)] optimizes the distribution of peak pressures and further mitigates the pressure amplitudes. The vents significantly contribute to the reduction of pressure transients within the enclosed noise barrier, presenting a promising solution for alleviating train-induced aerodynamic pressure in railway enclosed noise barriers.</p>