A system and a controlling method for extinguishing a fire in a battery of a vehicle is provided for preventing the vehicle from being completely burned out and protecting consumer's physical assets by injecting cooling water of a water cooling system when a fire occurs in a battery to extinguish the fire of the battery at an early stage and by supplying an external cooling material from outside of the vehicle to extinguish the fire of the battery when the fire of the battery is not extinguished at the early stage.