The invention discloses a method for data buffering when slowly playing medias, when slow play is selected by the user, the player receives data while performs decoding play with speed corresponding to user selected slow play multiple, according to bulk of received data, the player distributes buffering space capable of buffering the received data and buffers the received data into the distributedbuffering space. The player of the invention acquires playing buffer bulk according to bulk of the received data, which ensures no frame loss during slow play and continuity of playing images, meanwhile, waste of system memory source is avoided, which brings users better experience and improves service quality of mobile multimedia broadcasting system.