Abstract: In order to improve the bit-error-rate performance of the single-minimum Min-Sum algorithm for decoding Low-density parity check(LDPC) codes, the IMS-WVN(Improved Min Sum algorithm based on weighted message LLR of variable nodes) was proposed in this paper. firstly, determined the estimation parameter of the sub-minimum value accorded to the number of decoding iterations, and added the minimum value to replace the sub-minimum so as to enhance the reliability of the check-node. Secondly, the currently message of variable-to-check node and the message of old variable-to-check node were weighted to decrease the oscillation of the variable node and decrease the average number of decoding iteration. The simulation results show that the IMSWVN algorithm had improved 0.53 dB than VWMS algorithm and the 3.2 dB order of error rate, when the error rate was 10.5, The average number of iterations of the IMS-WVN algorithm is 58% less than that of the MS algorithm.