Fuente: Wipo "IOT" The present invention relates to a method and system for detecting an anomaly of an IoT weather sensor device based on sensor data fusion, more specifically, to a method and system for detecting an anomaly of an IoT weather sensor device by converging various weather sensor data received from IoT (Internet of Things) devices in a smart city environment. According to the present invention, in the provided method, abnormal numerical values of weather sensor data are calculated and collected without being affected by a specific value according to a place where the IoT device is installed and a time when the sensor data is measured by combining specific weather sensor data of an IoT device detecting an anomaly, other weather sensor data of the IoT device, weather sensor data of other nearby IoT devices, and past weather sensor data generated and stored in the server, so that abnormality of the weather sensor device is optimally determined. COPYRIGHT KIPO 2023