A method for transmitting data using a tail time in a cellular network comprising steps of: receiving a data transmission request from a mobile terminal, and inserting the data transmission request into a real-time request queue or a delay-tolerant request queue according to a type of the data transmission request; determining a tail time according to a state of a RRC state machine and a throughput of the mobile terminal; and obtaining the data transmission request to be transmitted from the real-time request queue or the delay-tolerant request queue, and transmitting the real-time data transmission request directly as there are real-time data transmission requests in the real-time request queue, and transmitting the delay-tolerant data transmission request using the tail time when the tail time is available for transmitting data or transmitting the delay-tolerant data transmission request directly when a deadline of the delay-tolerant data transmission request is approached.