In order to study the cooling effect of the surrounding rock construction of the ultra-long tunnel based on spray cooling, this paper relies on the Zhongliangshan tunnel project and adopts the numerical simulation method to analyze the characteristics of the tunnel average temperature change under different spray volume, the characteristics of the spray evaporation efficiency and temperature drop change under different humidity, and the characteristics of the tunnel average temperature change under different spray position. The results show that: (1) the average temperature in the tunnel decreases with the increase of the spray amount, and the higher the spray amount, the lower the temperature in the tunnel; (2) The greater the moisture content in the air, the smaller the temperature drop after spraying, and the greater the relative humidity of the tunnel air; (3) At the same time of spraying, the farther away from the palm surface, the smaller the temperature reduction; (3) The average temperature of the measured air temperature is not much different from the average temperature of the simulated value, which can be considered that the measured air temperature and the simulated value are basically the same; (4) In the actual tunnel spray cooling project, the spray volume of the nozzle is appropriately increased to ensure that the moisture content of the air in the tunnel is not more than 30g/kg, and the nozzle layout spacing is about 15m, which can quickly and effectively reduce the temperature in the tunnel.