A method for transmitting a media stream in a video conference performed by a terminal comprising a browser, wherein the method comprises: • when the browser of the terminal access a conference server by using login information of a user, receiving, by the browser, a first select instruction, wherein the first select instruction is specifically selecting to-be-sent video and audio information from the terminal, and the first select instruction is entered by the user of the terminal (step 510); • receiving, by the browser, according to the first select instruction, a create instruction sent by a first WebRTC application of the terminal; • according to the create instruction, invoking, by the browser, an extended WebRTC interface, and determining a video sending attribute value and an audio sending attribute value that are of a constraint object in the extended WebRTC interface; • when the video sending attribute value is true, setting, by the browser, an attribute of a first video port that has received video information to a port only for receiving a video, and setting an attribute of a second video port that has not received video information to a port only for sending a video; • when the audio sending attribute value is true, setting, by the browser, an attribute of an audio port to a transmit and receive port; • adding, by the browser, information about the set port attribute to a first transmission request message, so that the first transmission request message comprises the port attribute information of the browser; and • sending, by the browser, the first transmission request message to the conference server according to the first select instruction by using the first WebRTC application of the terminal (step 520); and • when a first transmission response message that is sent by the conference server according to the first transmission request message is received, sending, by the browser, a second media stream to the conference server according to the port attribute information by using a corresponding port, wherein the second media stream comprises the to-be-sent video and audio information (step 530). • when the browser of the terminal access a conference server by using login information of a user, receiving, by the browser, a first select instruction, wherein the first select instruction is specifically selecting to-be-sent video and audio information from the terminal, and the first select instruction is entered by the user of the terminal (step 510); • receiving, by the browser, according to the first select instruction, a create instruction sent by a first WebRTC application of the terminal; • according to the create instruction, invoking, by the browser, an extended WebRTC interface, and determining a video sending attribute value and an audio sending attribute value that are of a constraint object in the extended WebRTC interface; • when the video sending attribute value is true, setting, by the browser, an attribute of a first video port that has received video information to a port only for receiving a video, and setting an attribute of a second video port that has not received video information to a port only for sending a video; • when the audio sending attribute value is true, setting, by the browser, an attribute of an audio port to a transmit and receive port; • adding, by the browser, information about the set port attribute to a first transmission request message, so that the first transmission request message comprises the port attribute information of the browser; and • sending, by the browser, the first transmission request message to the conference server according to the first select instruction by using the first WebRTC application of the terminal (step 520); and • when a first transmission response message that is sent by the conference server according to the first transmission request message is received, sending, by the browser, a second media stream to the conference server according to the port attribute information by using a corresponding port, wherein the second media stream comprises the to-be-sent video and audio information (step 530).