Based on finite field (GF(q)) additive group,a novel construction method with the advantages of simple construction an d easy implementation of quasi-cyclic low-density parity-check (QC-LDPC) cod es for optical communication systems is proposed in order to meet the increasing requirement on the transmission characteristics.The novel construction method c an flexibly adjust the code-length and code-rate,and furthermore,the complexit y of the encoding and decoding in lower.A regular QC-LDPC (4599,7) code to b e suitable for optical communication systems is constructed by applying the prop osed method.The simulation results show that at the condition of the bit error r ate (BER) of 10－7 and the same code rate of 93.7%,the net coding gain (NCG) of the constructed QC-LDPC (4599,7) code is 2.2dB more than that of the classic RS (255,9) code which has widely been appl ied in optical communication systems,and 0.47dB and 0.25dB more than those of the SCG-LDPC (3969,0) code constructed by the systematically constructed gal lager (SCG) construction method and the irregular QC-LDPC (3843,3) code resp ectively,and is 1dB away from the Shannon limit.Therefore,the novel QC-LDPC (4599,7) code has superior error-correction performance and is more suitable f or the high-speed long-haul optical communication systems.