A wireless communication system includes a receiving unit, a buffer unit, a determining unit, and an adjustment unit. The receiving unit receives a signal stream. The buffer unit is coupled to the receiving unit, for storing the signal stream by using a used depth. The determining unit is coupled to the receiving unit, for determining a signal receiving quality of the signal stream received from the receiving unit and accordingly generating a determining result. The adjustment unit is coupled to the determining unit and the buffer unit, for adjusting the used depth of the buffer unit according to the determining result.