Abstract: Abstract: Based on the fire dynamics theory and the fire characteristics of large transfer subway station, the FDS software (Zhengzhou university supercomputing center version 6.7.5) was used to carry out the fire numerical simulation on Zhengzhou Zijing Mountain subway station. Through the fire detection points arranged in each area of the platform floor, concourse floor, transfer floor, and stairs and escalators in Zijing Mountain subway station, the changes of visibility with time were analyzed when the fire was located in the platform floor of Line 2 on the fourth underground floor. According to the smoke visibility and speed reduction formula, the speed reduction coefficients at different time were calculated. Then, the evacuation speed reduction coefficients were imported into each area of the subway station evacuation model in Pathfinder (version 2020), and a comparative analysis was carried out with the case that without the speed reduction. In this way, a more accurate dynamic evacuation speed was obtained, and results showed that the two-storey escalator near the fire location was more likely to cause occupants' retention.

Key words: Key words: subway fire, FDS, smoke visibility, evacuation speed, reduction coefficient, Pathfinder