The utility model relates to a hot rolling line three-network integration system with favorable communication performance, and belongs to the field of hot rolling line communication technology. The system adopts the technical scheme as follows: the first layer is an industrial filed bus network (6, 7), the second layer is an internal storage mapping network (4, 5), and the third layer is the Ethernet (1, 2, 3); the industrial field bus network is connected with a programmable logic controller (PLC) via a network card, and is further communicated with the internal storage mapping network via the PLC; the internal storage mapping network is in communication with all of network nodes in the internal storage mapping network via a fiber optic network port and an internal storage mapping network card; and the Ethernet is communicated with the internal storage mapping network via the fiber optic network port and the internal storage mapping network card. The system provided by the utility model achieves high speed and stable communication, well integrates the three different communication devices and communication technology, has a good application effect in the hot rolling field, is stable in operation and low in operation cost, and facilitates purchase and upgrade.