Abstract: With the increase of the ventilation length, the ventilation resistance along the tunnel and the air leakage rate of the air pipe gradually increase, resulting in a harsh construction environment in TBM tunnelling, seriously endangering the safety of personnel during construction. In view of this, various research methods such as on-site measurement, data investigation and theoretical analysis are used to clarify the ventilation control standards for long-distance TBM construction in railway tunnels, which cover multiple indicators such as air supply volume, ventilation speed and sanitary safety, etc. When the ventilation length exceeds the dead-end ventilation limit distance of single fan, it is recommended to use the dead-end forced ventilation or combined ventilation scheme with an increase in the number of fans, and provide corresponding method for dividing the scheme phases. Appropriate improvement measures are developed based on potential issues that may arise during the three phases of combined ventilation. Based on the construction of the Zhongtianshan Super-long Tunnel Project, a combined ventilation scheme during tunnel construction is determined. The specific fan design is given through theoretical calculations of air volume and ventilation resistance. According to the field test results of ventilation speed, air temperature and harmful gases in the three phases of combined ventilation, it is recommended to optimize the ventilation effect by taking measures such as repairing air pipes and improving the TBM ventilation system.