Message transmission method and device

The present invention provides a message transmission method and device. The method comprises: an SDN controller sends a first flow table to a first virtual switch, when the first virtual switch receives a message sent by a first virtual machine to a second virtual machine, the first virtual switch sends the message to a virtual router through a VXLAN tunnel built between the virtual router and the first virtual switch; when the SDN controller receives the message sent by the first virtual machine to the second virtual machine, a second virtual switch corresponding to the second virtual machine is obtained, and a second flow table and a third flow table are generated; the SDN controller sends the second flow table to the virtual router, and when the virtual router receives a message, the virtual router sends the message to the second virtual switch through a VXLAN tunnel built between the virtual router and the second virtual switch; and the SDN controller sends the third flow table to the second virtual switch, and when the second virtual switch receives a message, the second virtual switch sends the message to the second virtual machine. The problems of time delay, packet loss and the like of business access may be avoided.