Abstract: The advantages and disadvantages of various automatic fire extinguishing methods, such as water spray, water mist, gas fire extinguishing,aerosol, super fine dry powder system and local application mode, were compared systematically. The application conditions and scope of each system were discussed, and some application cases of fire-extinguishing system used in some utility tunnel projects in China were introduced. At the same time, it is proposed that the general branch or the imperfect pipe tunnel can be constructed step by step according to its economic conditions, and the manual, semi fixed or local fire extinguishing system should be set up first, and then further upgrading should be carried out when the conditions are met.

Key words: utility tunnel, fire extinguishing system, conditions of application