Method, device and system for data transmission

The invention discloses a method, a device and a system for data transmission. The method for the data transmission comprises the following steps of: classifying received group messages according to field information of preset fields in message headers; for each type of the group messages, packaging the field information of the preset field in the message header of one of the group messages into a spending domain of a data unit, and packaging the message payload of each group message and the field information of other fields beyond the preset fields in the message headers into a payload domain of the data unit; and sending the generated data unit to destination nodes of the group messages. The method, the device and the system can improve the bandwidth utilization ratio of a transmission link.