The application discloses a rendering method, a decoding method, a method and device for playing multimedia data flow. The rendering method comprises the following steps: drawing a transparent region on an interface if judging that at least one frame of image of the multimedia data flow has completely analyzed, and indicating the performing of the drawing of a playing window of the multimedia data flow and at least one frame of image of the multimedia data flow, wherein the transparent region and the playing window are overlapped on different drawing layers. By use of the rendering method disclosed by the application, the blurred screen phenomenon easily produced when starting playing the multimedia data through a drawn transparent region can be solved.