Numerous models have been proposed to reduce the classification error of Na(i)ve Bayes by weakening its attribute independence assumption and some have demonstrated remarkable error performance. Considering that ensemble learning is an effective method of reducing the classification error of the classifier,this paper proposes a double-layer Bayesian classifier ensembles (DLBCE) algorithm based on frequent itemsets.DLBCE constructs a double-layer Bayesian classifier (DLBC) for each frequent itemset the new instance contained and finally ensembles all the classifiers by assigning different weight to different classifier according to the conditional mutual information.The experimental results show that the proposed algorithm outperforms other outstanding algorithms.