Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in childhood, primarily characterized by inattention, impulsivity, and hyperactivity. With an estimated prevalence of approximately 8.0%, ADHD often persists into adulthood. Traditional explanations of its pathophysiological mechanisms mainly focus on abnormalities in the dopamine and norepinephrine pathways in the brain. However, a growing body of research is expanding the perspective to the microbiota-gut-brain axis (MGBA), revealing that the gut microbiota is involved in the pathogenesis and development of ADHD through neural, endocrine, and immune pathways. This article reviews recent advances in the understanding of the characteristics of the gut microbiota in children with ADHD, the MGBA pathways involved, and related intervention studies, aiming to provide insights for understanding the mechanisms of the gut-brain axis in ADHD and developing precise intervention strategies.