The embodiments of the present invention provide a method of constructing parity-check matrix of LDPC code. The method comprises the following steps of: constructing a MB×NB base matrix B for an LDPC code with code rate R and code length N, wherein MB=M/K, NB=N/K, M=N (1−R), K is the expansion factor of the base matrix, Kεφ, and φ is the set of the common factors of M and N; and replacing the elements of the base matrix B with a K×K matrix, and expanding the base matrix B into a parity-check matrix H with size of M×N for the encoding or decoding of the LDPC code. An encoding method and apparatus of LDPC code are also provided by the embodiments of the present invention. The technical solutions provided by the embodiments of the present invention can construct LDPC codes with good performance, solve the storage problem of the parity-check matrix, and effectively reduce the implementation complexity of the encoding apparatus.