Television (TV) picture split-screen expansion system

The invention discloses a television (TV) picture split-screen expansion system which comprises a main TV with a picture-in-picture (PIP) function, and an expansion display device connected with a video interface of the main TV. A multiplexing chip Mux used for converting audio and video data decoded by a decoding chip of the main TV into transport stream (TS) data flow through multiplexing synthesis and outputting the TS data flow to the video interface is arranged inside the main TV. According to the TV picture split-screen expansion system, the multiplexing chip Mux is arranged inside the main TV and used for converting the audio and video data decoded by the decoding chip of the main TV into the TS data flow through the multiplexing synthesis and outputting the TS data flow to the video interface of the main TV, then the TS data flow is output to the connected expansion display device through the video interface for being decoded and then output in a split-screen displaying mode, and therefore the display