NOVELTY - Shutting down a fuel cell system comprises determining whether an outside air temperature (S104) is below a first predetermined reference temperature when a shutdown of a fuel cell system is detected; warming up the fuel cell stack; removing water in the fuel cell stack by passing air supplied by an air supply system through the stack load to supply heated air to a cathode of the fuel cell stack (S108); and shutting down the fuel cell system (S118) by cutting off the supply of air (S113) after the removal of water.    USE - Shutting down a fuel cell system of vehicle. Uses include but are not limited to sports utility vehicles, buses, trucks, commercial vehicles, boats, ships, aircraft, hybrid vehicles, electric vehicles, and plug-in hybrid electric vehicles.    ADVANTAGE - The method can eliminate or reduce cold start failure. Water from the fuel cell system is effectively removed, when it is shut down at predetermined temperature or lower. Thus, the normal shutdown step of eliminating the voltage of the fuel cell stack is performed. The cold startability of the fuel cell system is improved.    DETAILED DESCRIPTION - Shutting down a fuel cell system comprises determining whether an outside air temperature (S104) is below a first predetermined reference temperature when a shutdown of a fuel cell system is detected; warming up the fuel cell stack by operating balance of plant components of the fuel cell system and a stack load using the power of the fuel cell stack, while the supply of hydrogen to the fuel cell stack is normally maintained, when the outside air temperature is below the first reference temperature; removing water in the fuel cell stack by passing air supplied by an air supply system through the stack load to supply heated air to a cathode of the fuel cell stack (S108); and shutting down the fuel cell system (S118) by cutting off the supply of air (S113) after the removal of water.    DESCRIPTION OF DRAWING(S) - The drawing is a flowchart illustrating water removal process and shutdown process of fuel cell system.    Determining outside air temperature (S104)    Supplying heated air to cathode of fuel cell stack (S108)    Cutting off supply of air (S113)    Cutting off auxiliary power source (S117)    Shutting down fuel cell system (S118)