The invention discloses a biological information identification method and a biological information identification system applied to building talk-back. The method comprises the following steps of detecting whether the authorization of selective call subscriber extensions is obtained or not when a gate host is communicated with the selective call subscriber extensions, and if yes, reading the biological information of subscribers by the gate host and storing into the selective call subscriber extensions as a biological information stub; receiving the biological information of the subscribers in real time by the gate host, and sending the biological information to all the subscriber extensions; comparing whether the biological information received in real time and the biological information stud are consistent or not by the subscriber extensions, and feeding back comparison results to the gate host; controlling a gate to be opened according to the comparison results. According to the biological information identification method and the biological information identification system applied to the building talk-back disclosed by the invention, the subscriber extensions can be expanded without the influence of the configuration of the gate host; the number of the subscriber extensions can be increased but the identification time of the system is not influenced; each subscriber extension and the gate host are all independent embedded systems; the comparison speed of the biological information is high; the comparison speed and the hardware cost can be reduced. The biological information identification method and the biological information identification system applied to the building talk-back have the advantages that capacity is flexible, the cost is low, operation is easy, the reliability is high, and the like.