A system including a transmission terminal, used for transmitting a target data packet obtained by encrypting and encapsulating a data flow; a network controller, deployed in a first Internet network and storing routing information from the transmission terminal to a receiving terminal; and a backbone transmission network device, deployed in a backbone transmission network and used for obtaining the routing information and the target data packet forwarded by the first Internet network and forwarding the target data packet to the receiving terminal based on the routing information. The present disclosure solves the technical problem of low efficiency and high cost of data transmission in the conventional techniques.