To study the cooling effect of spray cooling on the surrounding rock during the construction of an extra-long tunnel, based on the Zhongliangshan Tunnel Project, numerical simulations were performed to analyze the characteristics of average temperature variation in the tunnel under different spray rates, the evaporation efficiency and temperature drop characteristics of spray under different humidity levels, and the average temperature variation characteristics of the tunnel section under different spray positions. The measured values of the air temperature in the tunnel section were compared with the simulated values. The results indicate that: ① With the increase of the spray rate, the average temperature in the tunnel decreases gradually; when the spray rate is 0.038 kg/s, the temperature drops by 2.75 ℃ compared with the initial temperature of the tunnel; ② As air humidity increases, the droplet evaporation rate decreases gradually; when air humidity is 12 g/kg, the droplet evaporation rate is the highest compared to other humidity levels; ③ At the same distance from the tunnel face, when the air moisture content is 12 g/kg, the temperature drop after spraying is the largest compared with other moisture contents, with a maximum temperature drop of 7.06 ℃; ④ There is no significant difference between the average measured air temperature and the average simulated value, suggesting that the measured and simulated air temperatures are basically consistent. In actual tunnel spray cooling projects, the spray cooling system should be closely combined with the tunnel ventilation system. The position and air volume of the vents should be reasonably set to promote good air convection, while controlling the humidity in the tunnel to improve the cooling effect.