For quasi-cyclic low-density parity check (QC-LDPC) codes, the coding complexity is high and the selection of code-rate and code-length is not flexible, thus a deterministic structure is proposed based on the perfect cyclic difference sets. The number of shifts of base matrix (BM) can be obtained by a simple addition and subtraction. The combination of base matrix with special structure and the perfect cyclic difference sets saves the storage space and reduces the complexity of hardware implementation. The girth is at least six and the code-length and code-rate can be selected flexibly. Simulation results demonstrate that the net coding gain (NCG) of the irregular PCDS-QC-LDPC(2680,1340) code based on perfect cyclic difference sets is respectively improved by 0.13 and 0.32 dB compared with that of the code based on PEG-QC-LDPC(2680,1340) and AD-MASK-QC-LDPC(2680,1340) with the rate of 0.5 and the bit error rate (BER) of 10-6 by using the sum-product algorithm (SPA) iterative decoding in the additive white Gaussian (AWGN) channel.