Low-density parity check (LDPC) code is a linear block code approachin g the Shannon limit,and good irregular LDPC codes have better performance than regula r codes with the same code rate.In the log-likelihood ratio belief propagation (LLR-B P) decoding algorithm of irregular LDPC codes,due to the difference of the line size,the e xternal information contributed by the check node to the pseudo posterior decision is di fferent. Therefore,an improved LLR-BP decoding algorithm based on row weight is propose d.The algorithm introduces row weight coefficients to adjust the effect of different r ow weight external information and improve the decoding performance of the system.The sim ulation results show that at low signal-to-noise ratio,the improved log-likelihood r atio belief propagation decoding algorithm has almost the same decoding performance as the s tandard log-likelihood ratio belief propagation decoding algorithm.At medium and high signal-to-noise ratios,the improved LLR-BP decoding algorithm has better err or performance than LLR-BP decoding algorithm.When the code length is 64and the error rate i s 10－5,the improved LLR-BP decoding algorithm is compared with the traditional LLR-BP dec oding algorithm.The codinggain is increased by 0.15dB.