Provided are a data processing method, a terminal device and a network device. The method comprises: a terminal device receiving first indication information, used for code block segmentation, sent by a network device; the terminal device performing, according to the first indication information, code block segmentation on the data, so as to obtain at least one code block, wherein the data is data received by the terminal device from the network device, or the data is data to be sent by the terminal device to the network device; and the terminal device encoding or decoding the at least one code block. The embodiments of the present invention improve the flexibility of an encoding/decoding process.