A data processing method based on a quasi-cyclic LDPC, the method comprising: • calculating a length of an information bit section of the quasi-cyclic LDPC; • obtaining service data having a same size as a service data space in a storage unit; • when the size of the service data is less than the length of the information bit section of the quasi-cyclic LDPC, performing the following steps: ∘ calculating a difference value between the length of the information bit section of the quasi-cyclic LDPC and the size of the service data, and filling the service data with the same amount of known data as the difference value; ∘ constructing an initial parity-check matrix of the quasi-cyclic LDPC; ∘ performing elementary row conversion on the initial parity-check matrix; ∘ deleting, from bottom to top, a preset quantity of rows beginning from the last row of the initial parity-check matrix that has undergone the elementary row conversion, to obtain a new parity-check matrix, wherein the preset quantity is a difference value between a length of a check bit section of the quasi-cyclic LDPC and a redundancy check space size given by an organizational structure of the storage unit, wherein the length of the check bit section of the quasi-cyclic LDPC is calculated according to a formula ⌈ P z ⌉ ⋅ z − P, wherein P indicates the redundancy check space size in the storage unit, and z indicates a magnitude of a circulant matrix of the quasi-cyclic LDPC, and ┌ ┐ indicates round-up; ∘ coding the filled service data according to the new parity-check matrix to obtain redundancy check data corresponding to the service data; ∘ sending the service data and the redundancy check data to a corresponding physical location in the storage unit. • calculating a length of an information bit section of the quasi-cyclic LDPC; • obtaining service data having a same size as a service data space in a storage unit; • when the size of the service data is less than the length of the information bit section of the quasi-cyclic LDPC, performing the following steps: ∘ calculating a difference value between the length of the information bit section of the quasi-cyclic LDPC and the size of the service data, and filling the service data with the same amount of known data as the difference value; ∘ constructing an initial parity-check matrix of the quasi-cyclic LDPC; ∘ performing elementary row conversion on the initial parity-check matrix; ∘ deleting, from bottom to top, a preset quantity of rows beginning from the last row of the initial parity-check matrix that has undergone the elementary row conversion, to obtain a new parity-check matrix, wherein the preset quantity is a difference value between a length of a check bit section of the quasi-cyclic LDPC and a redundancy check space size given by an organizational structure of the storage unit, wherein the length of the check bit section of the quasi-cyclic LDPC is calculated according to a formula ⌈ P z ⌉ ⋅ z − P, wherein P indicates the redundancy check space size in the storage unit, and z indicates a magnitude of a circulant matrix of the quasi-cyclic LDPC, and ┌ ┐ indicates round-up; ∘ coding the filled service data according to the new parity-check matrix to obtain redundancy check data corresponding to the service data; ∘ sending the service data and the redundancy check data to a corresponding physical location in the storage unit. ∘ calculating a difference value between the length of the information bit section of the quasi-cyclic LDPC and the size of the service data, and filling the service data with the same amount of known data as the difference value; ∘ constructing an initial parity-check matrix of the quasi-cyclic LDPC; ∘ performing elementary row conversion on the initial parity-check matrix; ∘ deleting, from bottom to top, a preset quantity of rows beginning from the last row of the initial parity-check matrix that has undergone the elementary row conversion, to obtain a new parity-check matrix, wherein the preset quantity is a difference value between a length of a check bit section of the quasi-cyclic LDPC and a redundancy check space size given by an organizational structure of the storage unit, wherein the length of the check bit section of the quasi-cyclic LDPC is calculated according to a formula ⌈ P z ⌉ ⋅ z − P, wherein P indicates the redundancy check space size in the storage unit, and z indicates a magnitude of a circulant matrix of the quasi-cyclic LDPC, and ┌ ┐ indicates round-up; ∘ coding the filled service data according to the new parity-check matrix to obtain redundancy check data corresponding to the service data; ∘ sending the service data and the redundancy check data to a corresponding physical location in the storage unit.