Disclosed is a stereoscopic/multiview three-dimensional video processing system and its method. In the present invention, stereoscopic/multiview three-dimensional video data having a plurality of images at the same time are coded into a plurality of elementary streams. The plural elementary streams output at the same time are multiplexed according to the user's selected display mode to generate a single elementary stream. After packetization of the single elementary stream continuously generated, information about the stereoscopic/multiview three-dimensional video multiplexing method and the selected display mode information are added to the packet header of the stream. Then the packetized elementary stream is sent to the image reproducer or stored in storage media. The present invention multiplexes the multi-channel elementary streams having the same temporal and spatial information, thereby minimizing the overlapping header information, and performs streaming of data suitable for the user's demand and the user system environments.