In a data encoding method, for a first data stream obtained through outer encoding, inner encoding is performed on every consecutive k bits in the first data stream, where k is an odd number greater than 1. A total of (k−1)/2 bits may be obtained by performing an exclusive OR operation on every two of remaining bits other than one target bit in the k bits. Further, second FEC encoding is performed on a bit sequence that includes the (k−1)/2 bits and the target bit, to obtain p parity bits. n bits in an inner codeword obtained through inner encoding include the consecutive k bits and the p parity bits. In the data encoding method, an exclusive OR operation first and then encoding manner is used.