The present invention discloses a sub-frequency band sharing method, a base station and a user terminal. The method includes: assigning a unique terminal sequence code to a user terminal, and sending the terminal sequence code to the user terminal; receiving a user data packet sent by a core network; parsing the user data packet to acquire a destination user terminal to which the user data packet is to be sent; acquiring a terminal sequence code corresponding to the destination user terminal; acquiring an idle sub-frequency band in a frequency band, wherein the frequency band is divided into a plurality of sub-frequency bands, one or a plurality of base stations connected to the user terminal and a plurality of user terminals serviced by the one or a plurality of base stations share the sub-frequency band to transmit data; and modulating the user data packet and the acquired terminal sequence code to the idle sub-frequency band according to a predetermined sequence to form modulated data, wherein upon completion of the transmission of the modulated data, the sub-frequency band occupied by the modulated data is released. According to the present invention, a plurality of sub-frequency bands are shared between a plurality of user terminals and the base stations, and utilization rate of the frequency band is improved.