A power plug including an insulation main body is provided. A first pillar and a second pillar arranged at the insulation main body. Only a first channel for inserting a first plug terminal is defined on the first pillar and multiple second channels for inserting second plug terminals are defined on the second pillar. A power receptacle including an insulation base is provided. A first slot and a second slot respectively corresponding to the first pillar and the second pillar are defined at the insulation base. Only a first receptacle terminal is inserted in the first slot. Multiple second receptacle terminals arranged at interval and parallel with each other are inserted in the second slot. The first receptacle terminal and the second receptacle terminals are arranged in a row. The power plug and the power receptacle are thereby limited to correctly couple.