The invention relates to a carrier technology-based inter-substation area tie line backup power automatic switching communication system. The communication system includes backup power automatic switching devices, carrier devices, communication interfaces and communication modules; the backup power automatic switching devices are provided with the communication modules; the communication modules are connected with the carrier devices through the communication interfaces; each carrier device is connected with a corresponding 220kV substation; and two e carrier devices communicate with each other through any one phase of power line in existing power lines. According to the carrier technology-based inter-substation area tie line backup power automatic switching communication system, carrier technology is adopted, high frequency signals carrying information are loaded to the power lines, and the power lines are used for data transmission, and therefore, a large quantity of social costs and operating costs can be saved, and therefore, significant economic benefits can be brought about; when one substation is completely powered off due to voltage loss, an adjacent substation can supply power, and therefore, the two substations can be standby for each other.