The invention discloses a method for establishing session in an IP internet TV system, comprising the following steps: position information of a media server or parameter information corresponding to parameters of a media control channel of the media server is returned to a terminal, or the parameter information of the media control channel of the media server is returned respectively for a plurality of times so as to establish session connection between the terminal and the media server and conform to the treating principle of SDP. A session establishing system and a content positioning functional entity in an IP internet TV system are also disclosed.