The invention relates to a 
heterogeneous network technology of industrial real-time application, in particular to a 
time synchronization method oriented to a hierarchical 
heterogeneous network. A three-layer 
heterogeneous network consisting of an Internet 
backbone network, a 
wireless mesh backhaul network and a field 
Ethernet sub-network is constructed on the basis of hierarchical thought. An One_step 
time synchronization mechanism is adopted on the basis of the 
time synchronization principle of IEEE1588 and a hardware 
timestamp concept, so that a quarter of synchronization information 
packet transmission in a network is reduced; the network load is reduced; a hardware 
timestamp of a 
wireless network is introduced; and the time synchronization accuracy is increased. A boundary 
clock positioned on an interface between the 
wireless mesh backhaul network and a local 
Ethernet sub-network is designed on the basis of the abovementioned content in order to coordinate the time synchronization between the wireless mesh backhaul network and the local 
Ethernet sub-network, so that the problem of low time synchronization accuracy of the heterogeneous network due to different network protocols, synchronization 
information exchange and port inconsistency is solved. At last, whole-
network time synchronization is realized by adopting a hierarchical synchronization mechanism. On the basis of existing IEEE1588 and IEEE802.11 protocols, extra 
protocol overhead is not introduced.