As a crowded area with little underground space, when a fire breaks out at the platform level, smoke will travel up the stairwell to the concourse level, greatly jeopardizing the safety of the staff. A three-level subway interchange station in Qingdao is used as an example, and using the fire dynamics numerical simulation software FDS, it is examined how the smoke barrier, air curtain jet velocity, and mechanical smoke exhaust affect the spread of fire smoke in the event of a fire in the resting area of the negative third floor. The risk factor on the right side of the fire platform is larger than that on the left side of the platform, according to a comparison of temperature, CO concentration, and visibility changes caused by smoke spreading at the fire platform level. When the air curtain’s jet wind speed is set at 4 to 6 m/s under the same action as the smoke barrier, it can better limit the spread of smoke.