Abstract: In DC power supply network, communication among DC/DC converters is the key to guarantee the improvement of power supply efficiency and reliability. Aiming at the complexity of traditional power line communication circuit, a multi-carrier power signal composite transmission method based on low-frequency orthogonal frequency division multiplexing technology is proposed. By superimposing parallel carrier signals on reference voltage, low frequency ripples are injected into output voltage and multi-carrier signal modulation can be then achieved using single power converter. For Buck converters connected in parallel, the principle of multi-carrier PWM/ASK signal modulation and demodulation based on OFDM technology is analyzed, and the system stability and signal transmission characteristics are discussed. Experiments are presented to verify good feasibilities of the proposed signal modulation method.