Embodiments of the present invention solve in the prior art, in which a control side and a media side are not separated by a POC service, the problem of difficulty in subsequent technological advancements, failure to facilitate flexible implementation of services, also failure to facilitate system extension, and absence of a detailed process with regard to transmission-priority control when the control side and the media side are separated. Provided are a method and device for transmission-priority control. The method comprises: receiving, on the basis of a Mission Critical Push to Talk (MCPTT) server of a long-term evolution network, a first message transmitted by a user equipment (UE), where the first message comprises an identity of a group to which a speaker corresponding to the UE belongs and a parameter indicating a transmission-priority request as the event type; the MCPTT server produces a second message on the basis of the transmission-priority control policy and of the first message, where the second message comprises the identity of the group to which the speaker corresponding to the UE belongs and the parameter indicating the transmission-priority request as the event type, and the second message is used for instructing the UE to prompt the speaker to whom the UE belongs that transmission-priority has been awarded; the MCPTT server transmits the second message to the UE; the MCPTT server receives a response message transmitted by the UE in response to the second message; the MCPTT server produces a first instruction message on the basis of the response message in response to the second message, where the first instruction message is used for instructing a media resource functional entity to make an uplink voice changeover on a media side; and, the MCPTT server transmits the first instruction message to the media resource functional entity.