The present invention relates to the field of communications technologies, and discloses methods for transmitting and storing downlink data, a base station, and a terminal. In this solution, each time when a base station transmits downlink data, bits are selected in such a way that a length and a start point of a sequence that a terminal of any terminal category expects to receive in initial transmission (or retransmission) of a code block are the same as a length and a start point of a sequence that a transmit end determines to transmit for the same code block, so that the terminal can perform reliable decoding. Therefore, a disadvantage is avoided that the terminal cannot correctly perform storing and further cannot correctly perform decoding each time when the terminal stores a retransmitted code block for a same code block, and decoding accuracy of the terminal is improved.