A communicating system suitable for a repeater and communicating method thereof are described. The communicating system comprises a receiving unit, a delay module, a transmitting unit and a control unit. The receiving unit transmits a first signal based on a KB/MS input signal. The delay module is coupled to the receiving unit and delays the first signal from the receiving unit in order to generate a second signal. The second signal has a first phase difference in comparison with the first signal. The transmitting unit is coupled to the delay module and the control unit. The transmitting unit transmits a KB/MS output signal based on the second signal while the control unit controls the transmitting unit via a control signal. Specifically, the control unit is coupled to the receiving unit, the delay module and the transmitting unit such that the control unit generates the control signal based on the first signal from the receiving unit and controls the transmitting unit by inputting the control signal into the transmitting unit. That is, the control signal of the control unit triggers the transmitting unit to dominate output control of the delayed second signal of transmitting unit. The control signal generated by the control unit has a second phase difference in comparison with the first signal.