The invention discloses a system and a method for controlling the media stream of the multiparty video communication. The system includes a transmitting control path for media stream, a communicationterminal and a server. Therein, the communication terminal includes a RTCP unit, a RTP output unit, and a RTP input unit, a TS encoding unit, an I frame encoding unit, a media buffer unit, a TS decoding UNIT, an I frame decoding unit and a stream controlling unit. The server includes an I frame memory unit, a stream controlling unit and a communication sub-unit. The communication sub-unit includesaRTCP transmitting unit, a RTP output unit and a RTP input unit, an I frame extraction unit, a RTP de-packeting unit, a media buffer unit and a media source unit.; The invention also discloses a metho d for transmitting the static picture mixed with the TS stream and a method for seamless switching and controlling the media stream, which reduce the burden of the server and the communication terminal and provide enough information in order to reduce the process of the multiparty video communication.