Abstract: Solid combustibles in the meeting rooms of ships are numerous and densely packed. If a fire occurs, it is preferable for automated fire extinguishers and manual fire fighting methods to be used at the same time. If the situation demands that firefighters go to the scene, a water mist fire suppression system is necessary. In this paper, a model based on the pyrolysis kinetics of solid combustibles and the Large Eddy Simulation(LES) are used to investigate fires in an open-door ship's meeting room with a water mist fire suppression system, and the effects of different diameters of water droplets on the spread of the fire and the motion of the smoke are obtained. The simulated conditions are such that the initial velocity of the droplets equals 5 m/s, and the water mist fire suppression system is activated by the temperature sensors on the sprayers. When the average diameter of water droplets is less than 500 μm, the fire in the ship's meeting room is enhanced in the first stages of spraying. In order to meet the needs of both suppressing the fire and protecting the electric equipment, it is suitable for the average diameter of the water droplets to be between 500 μm and 750 μm.