This study examined the differential executive dysfunction of children with attention deficit hyperactivity disorder (ADHD) and those with ADHD and oppositional defiant disorder (ODD) in Han Chinese. A total of 258 children (89 ADHD, 53 ADHD + ODD, 116 controls) completed performance-based executive function tests and had their everyday life executive skills rated by their parents using the Behavior Rating Inventory of Executive Function (BRIEF). Both the ADHD and ADHD + ODD groups performed worse than the controls in the Stroop and Trail-making tests and the BRIEF. The ADHD + ODD group were rated worse than the ADHD group on the BRIEF, but the two groups showed no significant difference in the performance-based tests. These findings suggest Han Chinese children with ADHD display executive dysfunction in performance-based tests and everyday life scenarios, in a similar way to findings in Western counterparts. However, children with ADHD + ODD showed more severe executive dysfunction in everyday life scenarios than those with ADHD only.