An encoding method for a structured low-density parity-check, LDPC, code, applied in a 5th generation mobile communication, 5G, system, wherein the method comprises: 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, j is a column index of the base matrix, wherein Kb=Nb-Mb, Kb is an integer between 6 and 16 and Nb is an integer greater than or equal to 2xKb, i=1,..., Mb and j=1,..., Nb; 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 the number of Mb rows of the base matrix Hb, a numbers of columns of the upper-left submatrix Hb1 and a number of columns of the upper-left submatrix Hb2 both are smaller than the number of Nb columns of the base matrix Hb, and the upper-left submatrix Hb1 is an upper-left submatrix of the upper-left submatrix Hb2; wherein a number of entries corresponding to a ZxZ non-zero square matrix in each row of a submatrix consisting of an intersection of the last Kb-4 rows and the first Kb columns of the upper-left submatrix Hb2 is less than or equal to Kb-2; 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; characterized in that the upper-left submatrix Hb 1 consists of an intersection of the first four 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 Hb 1 is less than or equal to Kb+2 and greater than or equal to Kb-2, and a square matrix comprising the last four columns of the upper-left submatrix Hb1 corresponds to a (4×Z)×(4×Z) lower-left triangular matrix or a (4×Z)×(4×Z) quasi-lower-left triangular matrix; wherein the (4×Z)×(4×Z) quasi-lower-left triangular matrix corresponds to a (4×Z)×(4×Z) matrix which comprises a upper-right submatrix being a lower-left triangular matrix whose main diagonal entries are all ls. 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, j is a column index of the base matrix, wherein Kb=Nb-Mb, Kb is an integer between 6 and 16 and Nb is an integer greater than or equal to 2xKb, i=1,..., Mb and j=1,..., Nb; 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 the number of Mb rows of the base matrix Hb, a numbers of columns of the upper-left submatrix Hb1 and a number of columns of the upper-left submatrix Hb2 both are smaller than the number of Nb columns of the base matrix Hb, and the upper-left submatrix Hb1 is an upper-left submatrix of the upper-left submatrix Hb2; wherein a number of entries corresponding to a ZxZ non-zero square matrix in each row of a submatrix consisting of an intersection of the last Kb-4 rows and the first Kb columns of the upper-left submatrix Hb2 is less than or equal to Kb-2; 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; characterized in that the upper-left submatrix Hb 1 consists of an intersection of the first four 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 Hb 1 is less than or equal to Kb+2 and greater than or equal to Kb-2, and a square matrix comprising the last four columns of the upper-left submatrix Hb1 corresponds to a (4×Z)×(4×Z) lower-left triangular matrix or a (4×Z)×(4×Z) quasi-lower-left triangular matrix; wherein the (4×Z)×(4×Z) quasi-lower-left triangular matrix corresponds to a (4×Z)×(4×Z) matrix which comprises a upper-right submatrix being a lower-left triangular matrix whose main diagonal entries are all ls.