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 . <EOS>