The invention discloses a sub frame media data transmission method. The method includes that: firstly, a sending side sorts the present frames. A data buffer is divided into more than one data readingand writing area. And the present frames are written into relative positions of the data buffer according to a determined sequence. The second step is that the sending side reads the data buffer according to the sequence. And the read frames are sent to a receiving side. When the present read data reading and writing area and a data reading and writing area to be read after the present read datareading and writing area in the data buffer are judged to be separated to be the number of predetermined data reading and writing areas and the data reading and writing area to be read stores no unsent frames, compensating frames are written in the data reading and writing area. Through the method of the invention, the problems of frames lost, disordering, delaying, etc. on the network are solved.The speech mute problem is solved. The transmission quality of media data is improved. And the subjective feeling of terminals is greatly improved. The invention also discloses a sub frame media datatransmission system and a device.