Time synchronization system and method

The invention discloses a time synchronization system and method. The system comprises a frequency synchronization network and a time synchronization network, wherein the frequency synchronization network is used for transmitting a frequency synchronization signal to the time synchronization network after implementing frequency synchronization of every network element; and the time synchronization network is used for receiving the frequency synchronization signal from the frequency synchronization network, carrying out time counting according to the frequency synchronization signal to establish local time, and exchanging a time synchronization protocol message to calibrate the local time. According to the technical scheme disclosed by the invention, the high-precision time synchronization requirement can be satisfied; meanwhile, the time synchronization network and the frequency synchronization network are relatively independent logically in the aspects of frequency/time reference source selection mechanism, synchronous route computing mechanism and protective switching mechanism, and the layered architectures of the two networks in such a structure can be separated physically or logically; and thus, the system is very easy to maintain and manage, and the time synchronization network can be allocated according to the specific network environment, thereby enhancing the internetworking flexibility.