In order to meet the requirements of the high bit-rate and the lowe r bit error-rate of the error-correction code in optical communication systems,based on the balanced i ncomplete block design (BIBD) and the circulant decomposition in this paper,a novel construction method of quasi- cyclic low-density parity-check (QC-LDPC) codes with the advantage of the simple implementation i s proposed.A regular BIBDdes-QC-LDPC(6736,6316) code suitable for optical communication syst ems is constructed by applying the proposed method.The simulation results show that at the bit error rate (BER) of 10－6 and the same code rate of 93.7%,the net coding gain (NCG) of the constructed BIBDdes -QC-LDPC(6736,6316) code is 2.2dB more than that of the classic RS(255,9) code which has been widely used i n optical communication systems,and 0.2dB more than that of the BI BD-QC-LDPC(6736,6315) code with t he same code length and the same code-rate constructed only by the BIBD method and that of the irregular QC-LDPC(3843,3) code with the same code-rate based on Galois field multipli cative group.Therefore,the novel BIBDdes-QC-LDPC(6736,6316) code has superior error-correction perfo rmance and is more suitable for the high-speed long-haul optical communication systems.And the novel construction method still has the advantage of the BIBD method which can flexibly adjust the code length and code ra te.