A method for communication between private networks, performed by a cloud enterprise network, comprising: a process of creating a first sub-instance/a second sub-instance comprising: receiving (301,305), by a built-in master instance provided in the cloud enterprise network, a network registration request initiated by a first private network/a second private network; determining (302, 306) a first communication address/a second communication address of the first private network/the second private network based on the network registration request; returning (303, 307) a sub-instance creation instruction through the first communication address/the second communication address; and controlling (304, 308) the first private network/the second private network to create locally the first sub-instance/the second sub-instance for communicating with the master instance provided in the cloud enterprise network based on the returned sub-instance creation instruction, wherein after the creation of the first sub-instance/the second sub-instance is completed, the first sub-instance/the second sub-instance automatically establishes a respective first communication link/second communication link with the mater instance provided in the cloud enterprise network, receiving, through the first communication link between the master instance and the first sub-instance, a communication request sent by the first sub-instance provided in the first private network, the first sub-instance being created based on that the first private network initiates the network registration request to the master instance; determining a second private network as a destination based on the communication request; and sending, through the second communication link between the master instance and the second sub-instance, the communication request to the second private network through a second sub-instance provided in the second private network, the second sub-instance being created based on that the second private network initiates the network registration request to the master instance, wherein the first private network, the second private network, and the cloud enterprise network provided with the master instance forms a star topology centered on the cloud enterprise network. a process of creating a first sub-instance/a second sub-instance comprising: receiving (301,305), by a built-in master instance provided in the cloud enterprise network, a network registration request initiated by a first private network/a second private network; determining (302, 306) a first communication address/a second communication address of the first private network/the second private network based on the network registration request; returning (303, 307) a sub-instance creation instruction through the first communication address/the second communication address; and controlling (304, 308) the first private network/the second private network to create locally the first sub-instance/the second sub-instance for communicating with the master instance provided in the cloud enterprise network based on the returned sub-instance creation instruction, wherein after the creation of the first sub-instance/the second sub-instance is completed, the first sub-instance/the second sub-instance automatically establishes a respective first communication link/second communication link with the mater instance provided in the cloud enterprise network, receiving (301,305), by a built-in master instance provided in the cloud enterprise network, a network registration request initiated by a first private network/a second private network; determining (302, 306) a first communication address/a second communication address of the first private network/the second private network based on the network registration request; returning (303, 307) a sub-instance creation instruction through the first communication address/the second communication address; and controlling (304, 308) the first private network/the second private network to create locally the first sub-instance/the second sub-instance for communicating with the master instance provided in the cloud enterprise network based on the returned sub-instance creation instruction, wherein after the creation of the first sub-instance/the second sub-instance is completed, the first sub-instance/the second sub-instance automatically establishes a respective first communication link/second communication link with the mater instance provided in the cloud enterprise network, receiving, through the first communication link between the master instance and the first sub-instance, a communication request sent by the first sub-instance provided in the first private network, the first sub-instance being created based on that the first private network initiates the network registration request to the master instance; determining a second private network as a destination based on the communication request; and sending, through the second communication link between the master instance and the second sub-instance, the communication request to the second private network through a second sub-instance provided in the second private network, the second sub-instance being created based on that the second private network initiates the network registration request to the master instance, wherein the first private network, the second private network, and the cloud enterprise network provided with the master instance forms a star topology centered on the cloud enterprise network.