System for controlling air flow rate into vehicle engine room and control method thereof

A system for controlling an air flow rate into a vehicle engine room may include a fan shroud in which a cooling fan including a fan motor and a fan blade may be mounted, a rotary shutter which may be provided in the fan shroud while corresponding to an operation area of the fan blade, and in which an area through which air passes may be varied in a circumferential direction, a plurality of flaps which may be provided in the fan shroud, and opens and closes a part of a portion where the rotary shutter may be not mounted, and a control unit which controls an open area of the rotary shutter, operations of opening and closing the plurality of flaps, and an operation of the cooling fan in accordance with an operating state of a vehicle.