A real-time aerial gas detection and monitoring system is developed for air quality control in China Steel Corporation (CSC). A gas detection module is integrated with an quadrotor and the collected gas information is going to be delivered to a ground station through wireless communication. According to the measurement data, real-time and post analyses will be applied and the results could also be passed to product line for references and other applications. Moreover, image process technology is also integrated into the flight system such that a selected target could be detected automatically during the flight task. Finally, experiments are presented to demonstrate the main concept of the prototype system.