The present invention discloses a data sending method and apparatus. Herein, the method includes that: code block segmentation is performed on a physical layer source data packet, to be sent, having a length of K s bits, and channel coding is performed on each code block obtained by segmentation, to obtain C s error-corrected and coded source data sub-packets having lengths of K c bits; packet coding is performed on the error-corrected and coded source data sub-packets, to obtain Cp check data sub-packets; K i codeword bits are selected from the i th sub-packet in the C s source data sub-packets, K j codeword bits are selected from the j th sub-packet in the Cp check data sub-packets, all the selected bits are cascaded together to form a sequence having a length of formula (I), i=0, 1, ..., C s -1, j=0, 1, ..., Cp-1, and the sequence is sent, herein K s C s and K c are integers greater than 1, and Cp, K i and K j are integers greater than or equal to 0.