A method and a system for replacing media stream in a communication process of a terminal are disclosed. The method includes: a terminal issuing a request for replacing media stream to a communication server in a communication process; the communication server obtaining a corresponding replacing media source from a multimedia server according to a replacing media source identification carried in the request for replacing media stream, and replacing media stream sent by the terminal with the replacing media source. The system includes a multimedia server and a communication server. According to the embodiments of the present invention, a terminal participating in a communication process may replace its own voice and/or pictures with stored audio and/or video and/or data, so as to provide a new value-added service and bring new service revenue for operators.