A QC-LDPC decoder includes: a zero matrix monitoring circuit, configured to monitor whether a submatrix of a check matrix of QC-LDPC coding information is a zero matrix; a check node processing circuit, configured to calculate check message of the check node by using the check matrix according to variable message of a variable node if the submatrix is not a zero matrix; a variable node processing circuit, configured to update the variable message of the variable node according to the check message returned by the check node if the submatrix is not a zero matrix; and a check circuit, configured to determine whether the variable message satisfies a check standard or not.