Abstract: Ventilation during tunnel construction is an important guarantee for the physical and mental health of constructors and the safe and efficient construction of underground tunnel.According to the National Standards,the Water Resources Industry Standards,and the construction method adopted in Xianglushan Tunnel of the Central Yunnan Water Diversion Project,etc.,the ventilation and dust prevention sanitary control standards during tunnel construction were determined.Combined with the overall construction plan of the Xianglushan Tunnel and the layout of the branch tunnels,the ventilation program was planned.Through the calculation and analysis of the air supply,the volume of the air supply,diameter of the ventilation pipe,as well as power of the fan of each working face of tunnel were determined.On this basis,the typical section contructed by drilling and blasting and by TBM were selected for numerical simulation.The calculation results indicated that the wind speed of the ventilation pipe and the tunnel can meet the design ventilation standards,and the dilution effect of the pollutant in the tunnel was well.The feasibility and reliability of the ventilation design scheme of the project was verified.