A decoding method for parallel decoding of a codeword of a quasi-cyclic low-density parity check, QC-LDPC, code, where the QC-LDPC code is represented by a base matrix and an expansion factor L, wherein the method comprises: dividing, by a decoder, the QC-LDPC codeword C = { c 1, c 2, c 3,...,c n -1, c n} whose length is n into k QC-LDPC codeword segments D = { D 1, D 2,..., D k -1, D k}, wherein D i = { c ( i -1) l +1, c (i-1) l +2,..., c il -1, c il}, i = 1, 2,..., k - 1,k, and a length of D i is l = n / k = L; arranging, by the decoder, D i, i = 1,2,..., k - 1, k by column to obtain transpose QC-LDPC codeword segments D T = D 1 T, D 2 T,..., D k − 1 T, D k T, wherein D i T = c i − 1 l + 1, c i − 1 l + 2,..., c il − 1, c il T, i = 1,2,..., k -1, k; for each row j in the base matrix, performing cyclic shift on D i T, i =1,2,..., k - 1, k, according to a value in the j th row and i th column in the base matrix to obtain a shifted matrix E j of size l × k, wherein E j ∈ { E 1, E 2,..., E t -1, E t}, t is equal to a quantity of rows of the base matrix and j = 1,2,..., t - 1, t, and determining a ( t ∗ l) x k shift matrix E as combination of all shift matrices E j; obtaining, by the decoder, t ∗ m groups of QC-LDPC sub-matrices F 1, F 2,..., F tm -1, F tm according to the shift matrix E and a length d of the decoder, wherein each E j of E is divided into m groups, d denotes a quantity of parallel decoding operations, E j = E j 1 d, E j d + 1 2 d,..., E j m − 2 d + 1 m − 1 d, E j m − 1 d + 1 md = F j − 1 m + 1, F j − 1 m + 2,..., F jm − 1, F jm. E j s − 1 d + 1 sd, s = 1,2,..., m - 1, m, denotes the [( s - 1) d + 1] th row to the ( sd) th row of E j, and m = ⌈ l / d ⌉; and decoding, by the decoder, the t ∗ m groups of QC-LDPC sub-matrices to obtain a decoding result of the QC-LDPC codeword C. dividing, by a decoder, the QC-LDPC codeword C = { c 1, c 2, c 3,...,c n -1, c n} whose length is n into k QC-LDPC codeword segments D = { D 1, D 2,..., D k -1, D k}, wherein D i = { c ( i -1) l +1, c (i-1) l +2,..., c il -1, c il}, i = 1, 2,..., k - 1,k, and a length of D i is l = n / k = L; arranging, by the decoder, D i, i = 1,2,..., k - 1, k by column to obtain transpose QC-LDPC codeword segments D T = D 1 T, D 2 T,..., D k − 1 T, D k T, wherein D i T = c i − 1 l + 1, c i − 1 l + 2,..., c il − 1, c il T, i = 1,2,..., k -1, k; for each row j in the base matrix, performing cyclic shift on D i T, i =1,2,..., k - 1, k, according to a value in the j th row and i th column in the base matrix to obtain a shifted matrix E j of size l × k, wherein E j ∈ { E 1, E 2,..., E t -1, E t}, t is equal to a quantity of rows of the base matrix and j = 1,2,..., t - 1, t, and determining a ( t ∗ l) x k shift matrix E as combination of all shift matrices E j; obtaining, by the decoder, t ∗ m groups of QC-LDPC sub-matrices F 1, F 2,..., F tm -1, F tm according to the shift matrix E and a length d of the decoder, wherein each E j of E is divided into m groups, d denotes a quantity of parallel decoding operations, E j = E j 1 d, E j d + 1 2 d,..., E j m − 2 d + 1 m − 1 d, E j m − 1 d + 1 md = F j − 1 m + 1, F j − 1 m + 2,..., F jm − 1, F jm. E j s − 1 d + 1 sd, s = 1,2,..., m - 1, m, denotes the [( s - 1) d + 1] th row to the ( sd) th row of E j, and m = ⌈ l / d ⌉; and decoding, by the decoder, the t ∗ m groups of QC-LDPC sub-matrices to obtain a decoding result of the QC-LDPC codeword C.