The invention provides an interleaving and mapping method and a de-interleaving and de-mapping method of LDPC code word. The method includes: dividing the LDPC code word after coding into a plurality of continuous bit sub-blocks according to a predetermined length, transforming the arranging sequence of the bit sub-blocks according to a corresponding bit transformation pattern, and forming the LDPC code word after the first bit interleaving; writing in the LDPC code word after the first bit interleaving according to the column sequence and reading out and obtaining the LDPC code word after the second bit interleaving according to the row sequence; and performing constellation mapping of the LDPC code word after the second bit interleaving according to a constellation diagram in order to obtain a symbol stream. The interleaving mapping and de-interleaving and de-mapping methods are selected according to different LDPC code lists, and the system performance can be better enhanced.