Provided are a transparent clock passive port election method and device based on the PTP protocol. In the method, by extracting the TLV field of a received announce message, a first port of a network device acquires the clock identification information, forwarding times information and port identification information carried in the TLV field, and then compares the forwarding times information and clock identification information carried in the TLV field to the forwarding times information carried in the TLV field contained in a received announce message from a port by itself, and its own clock identification information, so as to select a port as a passive port. Therefore, by adding the comparison factors, such as clock identification information, forwarding times information and port identification information, in the TLV field of an announce message, a transparent clock is allowed to support the PTP protocol, thus avoiding a protocol storm formed by a PTP message in a complex topology network and a ring network constituted by the transparent clock to improve the stability of the network.