The invention discloses a data transmission method and a communication device. The method comprises the following steps: a sending end device processes a data stream, wherein the processing comprises:adding a stream identifier indication to the data stream, wherein the stream identifier indication is used for indicating whether a stream identifier is contained; and the sending end device sends the processed data stream. The invention further discloses the corresponding communication devices. By adoption of the technical solution of the invention, by adding the stream identifier indication tothe data stream, the stream identifier indication is used for indicating whether the stream identifier is contained, and transmitting the data stream according to the stream identifier indication, the processing of the data stream is completed.