This application provides a data processing method and a communications device. The data processing method includes: determining, by a first communications device, NCB, based on a size of the circular buffer of the communications device and an information processing capability of a second communications device; and obtaining, by the first communications device, a second encoded bit segment from a first encoded bit segment having a length of NCB. According to the data processing method and the communications device provided in this application, decoding complexity of the communications device can be reduced and communication reliability can be improved.