In this study, the stations on Seoul Metro line were categorized into 4 grades as a result of performing the smoke control safety evaluation that considered the conditions of platform air conditioning and exhaust system and mainline exhaust system in a bid to ensure the evacuation safety on platform and evacuation route to outside will be granted in a way of enhancing the efficiency of smoke control and exhaust system at subway stations. 4 stations were designated considering the safety evaluation grade and operation type of smoke control & exhaust system and then T.A.B was conducted. Consequently, the performance of existing smoke control & exhaust system appeared to have been far deteriorated from the design capacity.