Based on the construction principles of the low-density Parity-check code(LDPC)for optical communication systems,a novel construction method of the LDPC code is proposed,and the novel LDPC(3969,3720)code with 6.69% redundancy and the novel LDPC(8281,7920)code with 4.56% redundancy are constructed.The simulation results show that the net coding gain(NCG)of the two LDPC codes at the eighteenth iteration with the BER of 10-12 are respectively 1.63 dB,1.49 dB which are more than that of the RS(255.239)code in I...