ChatGPT has been demonstrated to possess significant capabilities in generating intricate, human-like text, and recent studies have established that its performance in theory of mind tasks is comparable to that of a nine-year-old child. However, it remains uncertain whether ChatGPT surpasses nine-year-old children in Chinese writing proficiency. To explore this, our study juxtaposed the Chinese writing performance of ChatGPT and nine-year-old children on both narrative and scientific topics, aiming to uncover the relative strengths and weaknesses of ChatGPT in writing. The collected data were analyzed across five linguistic dimensions: fluency, accuracy, complexity, cohesion, and emotion. Each dimension underwent assessment through precise indices. The findings revealed that nine-year-old children excelled beyond ChatGPT in terms of fluency and cohesion within their writing. In contrast, ChatGPT manifested a superior performance in accuracy compared to the children. Concerning complexity, children exhibited superior skills in science-themed writing, while ChatGPT prevailed in nature-themed writing. Significantly, this research is pioneering in revealing that nine-year-old children convey stronger emotions than ChatGPT in their Chinese compositions.