Objective  To explore the clinical characteristics of preschoolers with attention-deficit/hyperactivity disorder (ADHD). Methods  The subjects were 326 preschoolers (aged 4y0m-5y11m), diagnosed as ADHD according to the diagnostic infant and preschool assessment (DIPA) from the Diagnostic and Statistical Manual of Mental Disorders(Fifth Edition )(DSM-5). The diagnoses of subtypes (ADHD-I, ADHD-HI, and ADHD-C) were made by DIPA. The Chinese version of SNAP for preschool children, the strengths and difficulties questionnaire (SDQ), and the parent motivational questionnaire were assessed. Results  There were 271 boys and 55 girls in this study, with the ratio as 5∶1. There were 216 cases of ADHD-C, 81 ADHD-HI, and 29 ADHD-I. The ratio of three subtypes was 7∶3∶1. And 110 ADHD preschoolers (33.7%) had comorbidity, with the majority of them suffering from oppositional defiant disorder (ODD), accounting for 28.5% (93 cases). The results of the SDQ  (303 cases) indicated that 69.0% of the subjects had peer problems (209 cases). The results of the parental motivational questionnaire (253 cases) indicated that 202 parents (79.9%) had (strong) willingness to change. Conclusion  There are more boys with ADHD in preschool age, most of them are ADHD-C subtypes, with mainly comorbidity as ODD. The preschoolers with ADHD have prominent peer problems, and the parents have strong motivation for treatment.