Data transmission method and system for video session

The invention discloses a data transmission method and system for a video session, and belongs to the video session field. The technical scheme of the method comprises an invitation message that a multi control unit (MCU) sends to a media control unit comprising label information. The label information is used for identifying the type of an object needs to be transmitted. Based on a label, a transmission object corresponding to the label is transmitted in a transmission channel. The transmission channel adopted in the invention can be a uniflow channel; under normal circumstances, video information is transmitted in the uniflow channel; and when file data information, diagram data information and the like need to be transmitted, the data voice information is transmitted through adjusting the label and controlling the transmission channel. Therefore, through adopting the method and system in the invention, the data transmission based on video stream can be realized without adopting double flow transmission, and video session can be held between various terminals conveniently.