Managing the Power Internet of Things (IoT) presents challenges, particularly in the configuration of terminal devices. Power IoT terminals come in various types. Configuring each terminal on the IoT management platform and edge IoT agents involves a substantial amount of information, which has led to significant labor costs. This paper introduces an automatic registration technique for Power IoT terminals. Firstly, an intelligent identification program is employed to identify device information, including the manufacturer, type, model, and other device information. Subsequently, using this information, the triplet information is retrieved from the IoT management platform and synchronized to the registration server. Lastly, the device establishes communication with the registration server to acquire this information and successfully completes the automatic registration on the IoT management platform using the MQTT protocol. The proposed method addresses both the communication barrier between the IoT management platform and devices and the complex process of manual identification and configuration for terminal device registration. The effectiveness and feasibility of this approach in automatically registering Power IoT terminals provide robust support for the “plug-and-play” capability of new power devices.