Video conference system and signal processing method and device thereof

The invention provides a video conference system and a signal processing method and device thereof, and a medium, the system comprises a multi-point conference control unit MCU, the multi-point conference control unit MCU is at least connected with a first-level built-in MCU conference terminal, and the first-level built-in MCU conference terminal is at least connected with a second-level built-in MCU conference terminal; the backbone network adopts an E1 private line transmission mode, and the local area network adopts an IP network transmission mode; the digital signal processing units arranged in the first-level built-in MCU conference terminal and the second-level built-in MCU conference terminal complete call task access and audio and video, information and signaling processing. According to the method and the device, the conference terminals in various network forms can be collected to the maximum extent by the built-in MCU conference terminal, and the built-in MCU conference terminal calls and supports