A detailed analysis of the key technology of a real-time video network transmission system on Linux is made in this paper, which includes video capture, encoding, network transmission, decoding and playback. The system captures real-time video stream by USB camera, designs video capture program by Video4Linux APIs, according to MPEG4 algorithm, video stream is encoded by libavcodec APIs, then it's transmitted by JRTPLIB of stream media program method, decoded by MPEG4 algorithm and played back by SDL APIs. The embedded video transmission platform can be designed by integrating the embedded operating system.