A fuel cell system comprising: a cooling fan configured to cool a coolant; a pump configured to pump the coolant; and a controller communicatively connected with the cooling fan and the pump, wherein the controller is configured to: retrieve a preset cooling-fan RPM and a preset pump RPM, optimize the cooling-fan RPM and the pump RPM through a decrease of the cooling-fan RPM and an increase of the pump RPM such that a coolant temperature at an inlet of a fuel cell stack satisfies a specified temperature condition and a total power consumption is minimized, wherein the total power consumption is a sum of a power consumption corresponding to the cooling-fan RPM and a power consumption corresponding to the pump RPM, and store the optimized cooling-fan RPM and the optimized pump RPM, characterized in that the controller is further configured to: determine whether the coolant temperature at the retrieved cooling-fan RPM and the retrieved pump RPM exceeds a target temperature, optimize the cooling-fan RPM and the pump RPM to lower the coolant temperature to the target temperature or less when the coolant temperature exceeds the target temperature, and optimize the cooling-fan RPM and the pump RPM such that a difference between the coolant temperature and the target temperature is smaller than or equal to a threshold value and the total power consumption is minimized when the coolant temperature is lower than or equal to the target temperature. a cooling fan configured to cool a coolant; a pump configured to pump the coolant; and a controller communicatively connected with the cooling fan and the pump, wherein the controller is configured to: retrieve a preset cooling-fan RPM and a preset pump RPM, optimize the cooling-fan RPM and the pump RPM through a decrease of the cooling-fan RPM and an increase of the pump RPM such that a coolant temperature at an inlet of a fuel cell stack satisfies a specified temperature condition and a total power consumption is minimized, wherein the total power consumption is a sum of a power consumption corresponding to the cooling-fan RPM and a power consumption corresponding to the pump RPM, and store the optimized cooling-fan RPM and the optimized pump RPM, characterized in that the controller is further configured to: determine whether the coolant temperature at the retrieved cooling-fan RPM and the retrieved pump RPM exceeds a target temperature, optimize the cooling-fan RPM and the pump RPM to lower the coolant temperature to the target temperature or less when the coolant temperature exceeds the target temperature, and optimize the cooling-fan RPM and the pump RPM such that a difference between the coolant temperature and the target temperature is smaller than or equal to a threshold value and the total power consumption is minimized when the coolant temperature is lower than or equal to the target temperature. retrieve a preset cooling-fan RPM and a preset pump RPM, optimize the cooling-fan RPM and the pump RPM through a decrease of the cooling-fan RPM and an increase of the pump RPM such that a coolant temperature at an inlet of a fuel cell stack satisfies a specified temperature condition and a total power consumption is minimized, wherein the total power consumption is a sum of a power consumption corresponding to the cooling-fan RPM and a power consumption corresponding to the pump RPM, and store the optimized cooling-fan RPM and the optimized pump RPM, characterized in that the controller is further configured to: determine whether the coolant temperature at the retrieved cooling-fan RPM and the retrieved pump RPM exceeds a target temperature, optimize the cooling-fan RPM and the pump RPM to lower the coolant temperature to the target temperature or less when the coolant temperature exceeds the target temperature, and optimize the cooling-fan RPM and the pump RPM such that a difference between the coolant temperature and the target temperature is smaller than or equal to a threshold value and the total power consumption is minimized when the coolant temperature is lower than or equal to the target temperature. determine whether the coolant temperature at the retrieved cooling-fan RPM and the retrieved pump RPM exceeds a target temperature, optimize the cooling-fan RPM and the pump RPM to lower the coolant temperature to the target temperature or less when the coolant temperature exceeds the target temperature, and optimize the cooling-fan RPM and the pump RPM such that a difference between the coolant temperature and the target temperature is smaller than or equal to a threshold value and the total power consumption is minimized when the coolant temperature is lower than or equal to the target temperature.