Objective To study the characteristics of DNA methylation in children with attention deficit hyperactivity disorder （ADHD） using gene chip technology， and explore the role of DNA methylation in the pathogenesis of ADHD. Methods From October 2018 to May 2019， 8 children and adolescents aged 8 to 16， who were diagnosed with ADHD in the outpatient department of Beijing Anding Hospital Affiliated to Capital Medical University were randomly selected as the ADHD group. 8 healthy children and adolescents matched with ADHD group in age and gender were recruited as the control group. The Illumina Infinium Methylation EPIC Bead Chip （850K chip） technology was used to perform genome-wide DNA methylation detection， analyze and screen differentially methylated sites. Gene ontology （GO） enrichment analysis and pathway analysis were used for functional classification and pathway analysis of screened genes. Results A total of 2 068 CpG sites were altered in the ADHD group compared to the control group， and the difference was statistically significant （P＜ 0.05）. There were 842 hypermethylation sites， 1 226 hypomethylation sites， corresponding to 468 hypermethylation genes such as GPR88 and ARHGER10， and 705 hypomethylation genes such as SKI， PMP2， PRR12， EBF3， BRSK2， etc. GO enrichment analysis showed that differentially methylated genes were involved in biological processes such as phylogeny， neurological development， cell adhesion， etc. Pathway analysis showed that the differentially methylated genes were related to signal pathways such as cadherin signal pathway， neuronal system， Wnt signal pathway， glutamatergic synapse， etc. Conclusions Abnormal DNA methylation is involved in the occurrence and development of ADHD. The detected differential methylation genes may become biomarkers or predictors of ADHD. The signal pathways related to differential methylation genes may be related to the pathogenesis of ADHD.