Objective To explore the whole genome DNA methylation modification of impulsive aggression in patients with bipolar Ⅱ disorder. Methods The Illumina human 450k methylation chip technology was used to analyze the level of methylation of the whole blood genomic DNA samples of 5 cases of bipolar Ⅱ disorder patients with impulsive behavior and 5 cases of bipolar Ⅱ disorder patients without impulsive behavior. The R software was used to preprocess the raw data and select the differentiated methylation loci between sample groups. Finally， the GCBI online analysis software was used to analyze the functional enrichment of different candidate genes. Results （1）There was a difference in the methylation levels between the aggression group and the non-aggression group.（ 2）There was a difference in the distribution of methylation loci on the chromosome between the aggression group and the non-aggression group.（ 3）The differentiated methylation loci were classified by gene annotation classification and CpG island annotation classification， and the differentiated methylation loci were distributed in 11 annotation areas.（ 4）The result of GO analysis showed that the differentiated methylation loci participated in signal transmission and other functions. The pathway analysis showed that the affected function was mainly related with dopaminergic synaptic and chemokine signaling pathway. Conclusions In this study， the whole genomic DNA methylation levels and the distribution of methylated DNA on the chromosome in the aggression group were different from the non-aggression group.