An encoding method for a structured low-density parity-check, LDPC, code, applied in a wireless digital communication system, comprising: determining a base matrix Hb used for encoding, wherein the base matrix Hb comprises an Mb×Kb block A corresponding to a plurality of systematic bits and an Mb×Mb block B corresponding to a plurality of parity bits to have Hb=[A, B], and hb ij denotes an entry in an i-th row and a j-th column of the base matrix Hb, wherein i is a row index of the base matrix Hb, j is a column index of the base matrix Hb, wherein Kb=Nb-Mb, Kb is an integer greater than or equal to 6 and less than or equal to 16, Nb is an integer, i=1,..., Mb and j=1,..., Nb, and Nb is greater than or equal to 3*Kb; wherein the base matrix Hb comprises a plurality of submatrices, the plurality of submatrices comprises an upper-left submatrix Hb1 and an upper-left submatrix Hb2, a number of rows of the upper-left submatrix Hb1 and a number of rows of the upper-left submatrix Hb2 both are smaller than a number of rows of the base matrix Hb, a number of columns of the upper-left submatrix Hb1 and a number of columns of the upper-left submatrix Hb2 both are smaller than a number of columns of the base matrix Hb, and the upper-left submatrix Hb1 is an upper-left submatrix of the upper-left submatrix Hb2; and performing an LDPC encoding operation on a source information bit sequence according to the base matrix Hb and an expansion factor Z corresponding to the base matrix Hb to obtain a codeword sequence, wherein Z is a positive integer greater than or equal to 1; wherein the upper-left submatrix Hb1 consists of an intersection of the first 4 rows and the first Kb+4 columns of the matrix Hb, a number of entries corresponding to a Z×Z non-zero square matrix in each row of the upper-left submatrix Hb1 is Kb-2 or Kb-1 or Kb or Kb+1 or Kb+2, and a square matrix comprising the last four columns of the upper-left submatrix Hb1 is a lower-left triangular matrix or a quasi-lower-left triangular matrix. determining a base matrix Hb used for encoding, wherein the base matrix Hb comprises an Mb×Kb block A corresponding to a plurality of systematic bits and an Mb×Mb block B corresponding to a plurality of parity bits to have Hb=[A, B], and hb ij denotes an entry in an i-th row and a j-th column of the base matrix Hb, wherein i is a row index of the base matrix Hb, j is a column index of the base matrix Hb, wherein Kb=Nb-Mb, Kb is an integer greater than or equal to 6 and less than or equal to 16, Nb is an integer, i=1,..., Mb and j=1,..., Nb, and Nb is greater than or equal to 3*Kb; wherein the base matrix Hb comprises a plurality of submatrices, the plurality of submatrices comprises an upper-left submatrix Hb1 and an upper-left submatrix Hb2, a number of rows of the upper-left submatrix Hb1 and a number of rows of the upper-left submatrix Hb2 both are smaller than a number of rows of the base matrix Hb, a number of columns of the upper-left submatrix Hb1 and a number of columns of the upper-left submatrix Hb2 both are smaller than a number of columns of the base matrix Hb, and the upper-left submatrix Hb1 is an upper-left submatrix of the upper-left submatrix Hb2; and performing an LDPC encoding operation on a source information bit sequence according to the base matrix Hb and an expansion factor Z corresponding to the base matrix Hb to obtain a codeword sequence, wherein Z is a positive integer greater than or equal to 1; wherein the upper-left submatrix Hb1 consists of an intersection of the first 4 rows and the first Kb+4 columns of the matrix Hb, a number of entries corresponding to a Z×Z non-zero square matrix in each row of the upper-left submatrix Hb1 is Kb-2 or Kb-1 or Kb or Kb+1 or Kb+2, and a square matrix comprising the last four columns of the upper-left submatrix Hb1 is a lower-left triangular matrix or a quasi-lower-left triangular matrix.