A vehicle stereo system installed in a motor vehicle is disclosed to include a global positioning module that calculates the present location data of the motor vehicle, a memory device that has stored therein radio network records, each radio network record containing a plurality of geographic zones, and a plurality of receiving frequencies of a same radio network for use to receive radio programs of the same radio network in the respective geographic zones correspondingly, a vehicle stereo that has a tuner and a speaker, and a microprocessor that fetches the present location data of the motor vehicle, searches the memory device to find out a receiving frequency of the same radio network corresponding to the geographic zone, and controls the tuner to tune the vehicle stereo to the searched receiving frequency for output radio programs of the same radio network through the speaker.