The present invention relates to an apparatus, method and system for synchronizing time. The method includes: extracting line clock frequency information from an input line code stream, and extracting a time synchronization packet from a packet stream corresponding to the input line code stream; sending the input line code stream after extracting the line clock frequency information and the time synchronization packet to a packet switching device; receiving an output line code stream sent by the packet switching device; and calibrating local time according to the line clock frequency information and the time synchronization packet, recovering line clock frequency information of the output line code stream according to the calibrated local time, and inserting a time synchronization response packet into a packet stream corresponding to the output line code stream. In this way, the time synchronization network may be deployed without requiring the packet switching device to support time synchronization.