This study designed and developed a Chinese character handwriting diagnosis and remedial instruction (CHDRI) system to improve Chinese as a foreign language (CFL) learners' ability to write Chinese characters. The CFL learners were given two tests based on the CHDRI system. One test focused on Chinese character handwriting to diagnose the CFL learners' errors in the stroke order and their knowledge of Chinese characters, while the other test focused on the spatial structure of Chinese characters. Sixty-five participants, who had a strong desire to learn Chinese characters, voluntarily participated in this study. The results revealed that the CHDRI system enhanced the CFL learners' ability to write Chinese characters and to understand the spatial structure of Chinese characters, especially Sinosphere CFL learners. Moreover, it was found that remedial instruction materials not only reduced the amount of time the teacher spent coaching CFL learners in Chinese language learning but also facilitated the teacher's ability to provide feedback to individual learners.