The invention provides a data transmission method and device. The method comprises the following steps: finding a group having similarity with to-be-uploaded sensor data within a preset range from categories that are generated in advance, and uploading an identifier of the group and distinguishing data of the to-be-uploaded sensor data and the group. Compared with the prior art in which all to-be-uploaded sensor data are uploaded, the uploading data size can be reduced so as to save the flow. Further, the network load can be reduced, moreover, when a mobile network is used for sending data, as the sent data size is reduced, the use cost of the network can be reduced.