The invention discloses a multipoint safe videoconference system with an IP set-top box based on an H.323 protocol, which comprises a videoconference client module, a videoconference transmission module and a videoconference server module; the videoconference client module comprises the IP set-top box, a digital television and an audio / video acquisition and playing device and is used for realizing the identity verification of a videoconference user and the functions of acquiring, receiving and playing an audio / video content; the videoconference server module consists of a multipoint control unit (MCU) based on the H.323 protocol and is used for realizing functions of conference management, the integrity verification of the audio / video content, the identity verification of a user at a client, and the distribution and the processing of the audio / video content; and the videoconference transmission module realizes the transmission of the audio / video content between the user participating in a conference and a videoconference server by using a digital television network. According to the invention, a digital television user can realize a safe videoconference by the digital television with higher safety.