This application discloses an information processing method and apparatus, a communications device, and a communications system. The method includes: encoding an input sequence by using a low-density parity-check (LDPC) matrix, to obtain a bit sequence D, where a base matrix of the LDPC matrix is represented as a matrix of m rows and n columns, each column corresponds to a group of Z consecutive bits in the bit sequence D, and n and Z are both integers greater than 0; and obtaining an output bit sequence based on a bit sequence V, where the bit sequence V is obtained by permuting two groups of bits corresponding to at least two parity check columns in the bit sequence D.