In this paper, an illumination measurement system is proposed and experimentally demonstrated. The system consists of two parts, including the illumination acquisition module mounted on the UAV and the real-time display interface of the cloud platform with control functions. The illuminance acquisition module consists of a light sensor, a distance sensor, a wireless communication module, and a power-supply component. For the other part, the OneNET cloud platform developed by China Mobile is chosen as the display interface for the system’s real-time data. In addition, the local-outlier factor (LOF) algorithm is used for outlier rejection to further improve the stability and accuracy of the system. The illuminance acquisition system designed and implemented was then applied to the illuminance measurement experiments in the stadium. In experiments, the illuminance data acquired by the system was used to investigate the illuminance distribution at different height levels in the stadium. It was learned that the root mean square error (RMSE) of the data acquired is calculated to be 2.45 compared to the illuminance standard values through experimentation, with an error range of −2.77% to −0.53% for dynamic measurements.