Abstract: To optimize the spatial layout of sidewall jet fans in railway tunnels, taking UAE Railway Tunnel No. 10 as the engineering background, a computational fluid dynamics (CFD) method was adopted to investigate the effects of different spatial layouts on fan pressure rise performance as well as pollutant removal and cooling effects. The results indicate that the pressure rise performance of jet fans is mainly influenced by the deflection angle and suspension height, whereas the pollutant removal and cooling effects are significantly affected by the deflection angle and the distance from the sidewall. The pressure reduction coefficient of the jet fan first increases and then decreases with increasing deflection angle, and increases with increasing suspension height. Under high deflection angle conditions, the tunnel cross-sectional temperature and pollutant concentration are significantly higher than those under low deflection angle conditions. In addition, the closer the jet fan is to the sidewall, the lower the cross-sectional temperature and pollutant concentration. Considering both pressure rise performance and pollutant removal and cooling effects, the optimal lateral layout parameters are determined as a suspension height of 4D (D denotes the fan diameter), a distance from the sidewall of 0.25D, and a deflection angle of 10°. The reasonable range of longitudinal spacing between sidewall jet fans is 122-248 m, which should be adjusted in practical engineering according to variations in deflection angle and suspension height to achieve optimal ventilation performance.