School counselors should participate in the diagnosis and treatment of students with attention-deficit hyperactivity disorder. The purpose of this paper was to introduce 1. the basic concepts of ADHD; 2. the diagnosis of ADHD, and 3. the treatment of ADHD in order to provide references for counselors to clarify people's misconceptions of ADHD. The assessment techniques and diagnosis process of ADHD was introduced and focus on multidimensional assessments, and presented the comprehensive treatment program of ADHD, including medication treatment, parenting education, parent counseling, individual and group counseling, and study guidance.