Abstract: The combination rule of conflict evidences has been one of the important issues in Dempster-Shafer theory since it may conclude an error result in dealing with high conflict information.In order to deal with the problems that much of modified combination rules do not satisfy the associative law,a new combination rule that satisfies the associative law is proposed.An optimized model of evidence discount rate based on the minimized Ign(·) function is built firstly,then the modified evidences are obtained by pretreated mass functions with discount rate.Finally the modified evidences are combined by the new combination rule.The numerical example shows that the new combination rule has good performance in dealing with conflict and improves the reliability and rationality.