The present application discloses a method for data transmission in a radio cell of a mobile terminal. The radio cell includes an auxiliary carrier in a low frequency band and at least one master carrier in a high frequency band, the method including: the mobile terminal achieving downlink synchronization with the radio cell through the auxiliary carrier in the low frequency band, and after achieving the downlink synchronization, obtaining configuration information of the radio cell, and transmitting data by using the master carrier and/or the auxiliary carrier according to the configuration information. The present application also provides a mobile terminal. By using the present application, radio cell coverage and transmission performance may be improved.