Abstract: Abstract: Aiming at the fire protection of small car garages, a full-scale car garage fire experiment platform of 5.95 m×7.6 m×3.6 m was established. The water distribution performance of a single nozzle of high-pressure water mist fire-extinguishing system under different system working pressures （6, 8 ,10 MPa） was studied experimentally. Therefore, the design parameters and the arrangement position of the nozzles of the water mist fire-extinguishing system in the small car garage were analyzed and determined. Besides that，the determined water mist fire extinguishing system was used to carry out the fire-extinguishing test of the fire in the back seat of the car in the garage. The results showed that the high-pressure water mist fire-extinguishing system can suppress the development of the car fire in the small garage effectively, and can protect the enclosure structure of the garage and the adjacent car well. In this paper, it is determined that the high-pressure water mist fire-extinguishing system of the small car garage adopts a closed system, the working pressure of the system is 10 MPa, the design spray intensity is not less than 2.0 L/（min·m2）, the flow coefficient is K=3.0 and other design parameters as well as the arrangement position of the nozzle, which can make the fire extinguishing system achieve better fire extinguishing and fire control effect.

Key words: Key words: water mist fire-extinguishing system, water distribution performance, full-scale garage fire experiment, fire-extinguishing effectiveness