The embodiment of the invention provides switch equipment in a power distribution system, which is equipped with a multiphase power wire communication interface, and capable of selecting one phase wire from a plurality of phase wires as a designated phase wire according to the detected current information of each phase wire, and enabling the power wire communication interface to receive and transmit data on the designated phase wire. The embodiment of the invention further provides the power wire communication interface used for the switch equipment, as well as a method and a system for realizing power wire communication. By adopting the switch equipment and the power wire communication interface, method and system provided by the embodiment of the invention, wiring cost and maintenance cost can be reduced; and preferably, the power wire communication interrupt caused due to phase wire faults can be avoided simultaneously.