Research has proven that ADHD does not only manifest as hyperactivity, but can also co-occur with a variety of behavioral and psychological disorders, which, if not diagnosed in time and treated correctly, can affect the prognosis of the affected child, and may even have lifelong implications. Co-occurring disorders, or co-morbidities for short, are two or more different disorders that occur in the same individual. Some studies have reported that ADHD alone accounts for only 31% of cases, and 69% of cases are co-morbid with other psychiatric disorders, of which 40% are co-morbid with oppositional defiant disorder, 31% are co-morbid with anxiety disorder, 14% are co-morbid with conduct disorder, 11% are co-morbid with tic disorder, and 4% are co-morbid with mood disorder. The presence of co-occurring disorders makes the condition of children with ADHD more complex and the impact on social functioning more serious, so it is necessary to pay attention to the treatment of co-occurring disorders to improve the prognosis of ADHD. ADHD co-occurring disorders of oppositional defiant disorder and conduct disorder Oppositional defiant disorder is the most common co-occurring disorder in children with ADHD, and ADHD, oppositional defiant disorder and conduct disorder sometimes overlap with each other. Treatment is mainly psychological, behavioral and pharmacological. Medications used to treat ADHD (e.g., the central stimulant and norepinephrine reuptake inhibitor atomoxetine) are themselves effective in improving impulsive and aggressive behaviors in ADHD children with oppositional defiant disorder. Recent studies have shown that some of the newer antipsychotics can be effective in treating mood swings, temper tantrums, hyperactivity, aggression, and hypersensitivity in children with conduct disorder or oppositional defiant disorder. ADHD co-occurring mood disorders should be treated psychologically, and support from parents and teachers is very important. Although central stimulants may have a mild antidepressant effect, it is important to use antidepressants to treat children with ADHD who are moderately or severely depressed, or who are mildly depressed and whose depression does not improve with stimulants. Since atomoxetine is effective in treating ADHD and has a moderate antidepressant effect, it is an option for children with ADHD who have co-occurring depressive disorders. ADHD co-occurring tic disorders The treatment of such children begins with psychological support to reduce psychological stress. Tomoxetine treatment of ADHD at the same time generally does not aggravate the symptoms of tics, the clinical application of such children is more. Because central stimulants may aggravate the symptoms of tics, if the choice of central stimulants should start with a small dose, regular follow-up with the doctor to assess the appropriateness of the dose. Antitwitching drugs should also be chosen to treat tic disorders. The treatment of ADHD co-morbidities should be as comprehensive as that of ADHD, and the treatment of ADHD symptoms and co-morbidities should be placed in the same treatment plan and system when developing the treatment plan. Medication should be only one component, and this integrated treatment should include a variety of other interventions (e.g., parent counseling and psychobehavioral therapy).