The utility model discloses an Internet of Things door magnetic alarm based on network disconnection detection, which comprises a door magnetic switch, an Ethernet interface, a network cable switch, anetwork module and an alarm module, the network module is communicated with the Ethernet interface through the network cable switch, and the door magnetic switch is in trigger connection with the network cable switch; when the door magnetic switch is triggered to be disconnected, the network cable switch disconnects the alarm module to give an alarm. According to the utility model, the door magnetic alarm is realized by utilizing the network disconnection detection and the Internet of Things technology, the transmission distance of the alarm signal is not limited theoretically, and the alarmsignal can be sent to the alarm receiving terminal as long as there is a network. The anti-theft alarm is widely applied to alarming of various doors, windows, drawers, movement forbidding and the like.