Purpose: Poor writing is common in children with attention deficit hyperactivity disorder (ADHD). However, the writing characteristics of ADHD children are not being discussed in Chinese. It is worthy to do further research on the writing difficulties of the ADHD children in Taiwan. Method: This paper used standardized measures of composition to evaluate the ADHD children's ability of writing performance, and then analyze the productivity, the syntax quotient and the level of abstraction. The participants included 21 children with ADHD and 21 normal children. Result: Words (in average) in a sentence, total words in a paragraph, and levels of meanings were poorer than normal children, whereas the ADHD children's lexical errors wasn't more than normal children. Besides, the ADHD children made more errors in the omission of punctuation and the addition of a radical or a stroke in Chinese characters than normal children. Finally, the ADHD children wrote paragraphs less than normal children and showed the lack of organization in the composition. Conclusion: The difficulties faced by children with ADHD in producing more paragraphs could be due to their well-known planning and organizational difficulties. However, the spelling errors in children with ADHD could be associated with their attention deficit.