Previous studies have shown that impaired goal-directed alpha lateralization and functional disconnection within attention networks during the cue period are significant features of attention-deficit/hyperactivity disorder (ADHD). This study aimed to explore the role of brain oscillations in the visual search process, focusing on target-induced posterior alpha lateralization, midfrontal theta synchronization, and their functional connection in children with ADHD. Electroencephalograms were recorded from typically developing (TD) children (n = 72) and children with ADHD (n = 96) while they performed a visual search task. Both the TD and ADHD groups showed significant midfrontal theta event-related synchronization (ERS) and posterior alpha lateralization. Compared with TD children, children with ADHD showed significantly lower theta ERS and higher target-induced alpha lateralization. TD children showed a positive trial-based correlation between theta ERS and alpha lateralization and a negative correlation between theta ERS and reaction time variability. However, all these correlations were absent in children with ADHD. Abnormal brain oscillations in children with ADHD indicate insufficient executive control function and the compensation of attention networks for attention deficits in visual selective attention. Cross-frequency disconnection reflects the common deficiency of executive control in the gating of target information. Our findings provide novel evidence for interpreting the features of brain oscillations during stimulus-driven selective attention in children with ADHD.