An event alarm device includes a sensor, a notification unit, a MESH communication unit, an NB-IoT communication unit, and an MCU. The NB-IoT communication unit is configured to upload the data measured by the sensor. The MCU is configured to detect a specific event according to the data measured by the sensor. When detecting the specific event, the MCU is configured to instruct the notification unit to emit an on-site alarm, instruct the NB-IoT communication unit to send a first warning signal, and instruct the MESH communication unit to send a second warning signal.