The present application discloses a DECT base station, mobile terminal and system for transmitting data frame. The DECT base station comprises the first codec module and the first RF module. The first codec module is configured to store the acquired encoded data frame in the encoding buffer area of the first codec module; wherein, between the length of the encoded data frame and the length of a B-field data in the TDMA frame, there is a multiple relationship. The first RF module is configured to send, when receiving the first trigger signal, the encoded data frame in the encoding buffer area to mobile terminal. The present application can transmit data frame under the action of the trigger signal, to ensure the completeness and effectiveness of the data frame, thereby increasing the number of broadband voice communication channels.