Abstract: The parallel decoding system with multiple sub-decoders has much performance improvement than that of single-decoder system for decoding the block codes. However, the construction of sub-decoders for the parallel decoding implementation is still the challenging problem. To solve this problem, this paper proposes a parallel decoding method with multiple sub-decoders based on BP (belief propagation) algorithm for some specific low-density parity-check (LDPC) codes. This method is particularly effective for decoding the LDPC code generated via primitive polynomial. The method has characteristics as the parity-check matrix used for each sub-decoder depends on a proper cyclic shift of the original parity-check matrix, and the number of cyclic shift depends on the sampling property of the m sequence (which uniquely corresponds to a primitive polynomial). The iteration times of each BP processes in the sub-decoder are set as half of the girth of Tanner graph of the parity-check matrix, thus the affection of short cycles on BP performance would be eliminated. The output extrinsic information for each bit generated by the sub-decoder is processed further by a decoding module to output the candidate codeword, and then the LMS module picks out the maximum likelihood candidate codeword as the output of the decoding system. The simulation results show that the performance of the proposed parallel decoding method with 5 sub-decoders is about 0.4 dB superior to that of the original single-decoder decoding method at the bit error rate of 10⁻⁵.