The application provides a synergetic networking system based on a power line communication and a communication method. The system comprises a power line network, a sending device and a receiving device, wherein the sending device comprises at least two programmable logic controller (PLC) modulator-demodulators connected through a power line chain. When a power line channel between the PLC modulator-demodulator for sending signals in the sending device and the receiving device is not the optimal channel, the PLC modulator-demodulator used for sending signals to the power line channel between the PLC modulator-demodulator and the receiving device through a wireless chain is better than the other PLC modulator-demodulator between the PLC modulator-demodulator itself and the receiving device; the PLC modulator-demodulator transmits the signals to the receiving device through a power line network. By adopting the system and the method provided in the application, the reliable and effective transmission of every PLC modulator-demodulator in the sending device is guaranteed, the reliability and the effectiveness of a power line communication system are improved.