The problem of hot and humid environment occurs during the TBM driving of Zhongtianshan extralong tunnel on the second line of TurpanKorla section of Nanjiang railway. In the paper, the causes for the hot and humid environment, as well as the influence of the high temperature and humidity on the labors and equipment, are analyzed, and it is concluded that the key factor to be considered in the determination of the dehumidification cooling load is the heat emitted by the electrical equipment. The mathematical model of hot and humid environment is established. The dehumidification load for the TBM driving of Zhongtianshan tunnel is analyzed and it is concluded that the dehumidification cooling load needed at the working face of Zhongtianshan tunnel is 1 192.3 kW. Proper cooling pump modes and equipment parameters are proposed for the control of the hot and humid environment in Zhongtianshan tunnel. The paper can provide reference for the analysis and calculation aimed for the control of the hot and humid environment in tunneling by TBM. 