Disclosed are a carrier communication method based on electric automobile charging/discharging, comprising the following steps: S1: after being powered up and started, an electric automobile detecting whether a carrier signal from a peripheral device is received through an interface wire harness and whether the carrier signal is correct; S2: when detecting the carrier signal and detecting that the carrier signal is correct, the electric automobile receiving the carrier signal through the interface wire harness; and S3: the electric automobile performing coupling and filtering on the received carrier signal to convert the carrier signal into a standard carrier signal, and demodulating the standard carrier signal into a digital signal to obtain information of the peripheral device. The method, on the basis of not increasing the number of wire harness, may implement data transmission and sharing between an automobile and ECU modules of a peripheral device, and carrier communication with other signal lines as communication media at the same time, so as to avoid construction and investment of a new communication network, and reduce manufacturing cost and maintenance difficulty. Further disclosed are a carrier communication system and a carrier apparatus based on electric automobile charging/discharging.