The invention discloses a fully-digitalized building intercom system, wherein a control module forms an LAN (Local Area Network) together with user indoor computers and a management center computer through a network adapter and a switch, and the intercom system is installed on each stairway entrance and is used for calling each user indoor computer or the management center computer; when an owner wants to enter an iron gate in the stairway, a fingerprint identification sensor collects a fingerprint and identifies the identification after the fingerprint is processed by a fingerprint data processing module; the control module controls an electronic control door key to be automatically unlocked after the identification is identified; a visitor calls a tenement through the intercom system, and the tenement unlocks the stairway door key through remote control after processing and identifying the visitor by an audio processing module and an image processing module; in addition, the management center computer sets system parameter inquiry through a web server in the intercom system. The invention has the characteristics of high integrated level, small size and the like and overcomes the defects of the conventional analog system.