System and method for emergency starting fuelcell vehicle

Disclosed are a system and method for starting a fuel cell vehicle in an emergency, comprising: a high voltage converter having one side to be connected to a high voltage battery by a battery switch and the other side to be connected to a fuel cell in parallel; a balance-of-plant (BOP) connected to the high voltage converter and the fuel cell in parallel; and a controller for controlling to supply power of the high voltage battery to the BOP without converting by connecting the battery switch when the high voltage converter or the high voltage battery are broken.