We propose a method of controlling buffer dynamically for fast audio & video control response and bandwidth adaptation on Internet streaming application. When A/V control occurs, the proposed method designs an efficient transmission data control mechanism, and also takes network bandwidth adaptation into consideration at the server side, so that users may watch streaming video smoothly with stable quality. Moreover, the player side may playback without interruption and re-buffer automatically without any extra effort. The advantages are, (1) fast A/V control response, which greatly improves usability and user perception; (2) stable quality and buffer adaptation, which keeps steady quality even applied in changing Internet environment.