In order to meet the communication requirement that emerges from the joint debugging process between station and station or plant and station for regional stability control system, this paper proposes a method for transmitting video-audio data on-spot via the idle bandwidth of the data transmission channel of regional stability control systems and analyzes the differences between communications of regional stability control systems and video-audio data packets. What’s more, it gives a coding algorithm which mix coded two different data types and a distortionless real-time separation recognition algorithm. At last, it uses priority designated method to solve the contradiction between data timeliness of the stability control systems and excessive video-audio data traffic, in addition, establishes an actual stability control system model (one-to-one or one-to-many) for experimental verification. The test results show that stability control system works safely and reliably, the image transmission is smooth and clear, and using the method mentioned above has significantly improved the utilization of the communication channel. The research achievement has been used in the stability control systems of 220 kV Duanzhou transformer substation and 1120 MW Yunfu power plant, which effectively improves the efficiency and the accuracy of the stability control systems joint debugging, and provides a great convenience in the day-to-day operation and maintenance monitoring.