To establish large deployable antenna reliably and accurately in space, a space visual-monitor system was researched. Using the system, the deployment of the antenna could be monitored real-time, and an analysis was made for dynamics on the deployment process, which was very necessary for designing large flexible deployable structures, detecting the anomalies and analyzing the possible reason. Based on the research on system task, the system project was introduced, including camera choice, visual information transfers way, image processing method and analog modulating scheme. Not only the key technology was researched, including image detection and recognizing for moving target and deploying dynamics analysis way, but also the validity of the technology by experiment was verified. The result of the experiment proved the space visual-monitor system including the key technology could complete the task of monitoring, measurement and analysis.