This study simulate the evacuation from structural steel manufacturing building and verified with Thai’s regulation. According to the regulation, all occupants shall be in safe place within 5 minutes in case of fire incident. Two simulation scenarios were selected for this simulation. First, all exits can be used for evacuation; evacuation time is 4.23 minute after announcement. Second, fire caused by explosion of compressed air tank near Exit A, which completely block this exit A. Simulation result shown that evacuation time for this particular case is 7.06 minute, which is exceed maximum evacuation time defined in the regulation. Therefore, the following countermeasures are propose: Expand existing stair from 1.0 m to 1.5 m., Install an additional stair with the same width on the opposite side and modify firefighting procedure.