Cross-network data transmission method and cross-network data transmission system

The invention provides a cross-network data transmission method, which comprises the following steps that: when target ferry data meeting a target ferry data rule in a first database in a first information site is changed, a ferry data generation module generates a corresponding operation record, writing the operation record into a target ferry log file corresponding to the target ferry data rule; when cross-network data transmission needs to be carried out, the ferry data generation module generates a ferry data packet and sends the ferry data packet to the data review and cross-network transmission module; the data review and cross-network transmission module performs security review on each target ferry log file in the ferry data packet, and writes the ferry data packet into a data storage carrier after the security review is passed; and the ferry data redo module reads the ferry data packet in the data storage carrier, and performs redo operation on a second database in a second information site according