The present invention provides a system & method for controlling a radiator flap for a vehicle, which are capable of effectively operating of a cooling fan and a radiator flap simultaneously consequently by opening & closing the radiator flap by a combination of a cooling fan control signal related to control of the cooling fan and a vehicle CAN signal related to vehicle state information, such as a vehicle speed. The system includes: an engine controller that is configured to generate a cooling fan control signal. In addition, an integrated controller is configured to detect an engine coolant temperature based on the cooling fan control signal, and detect one or more of vehicle speed information, on/off information of an air conditioner switch, and air conditioner refrigerant pressure information based on a vehicle CAN signal to open and close the radiator flap.