The Secondary Chinese language curriculum in Singapore is divided into five courses to tailor to students’ language proficiencies. The courses, in descending proficiency, are Higher Chinese, Express Chinese, Normal Academic Chinese, Chinese B, and Basic Chinese. The 2021 Singapore Chinese Language syllabus uses an integrated design, where the five courses are differentiated yet unified under the same design. Readability is a measure of text difficulty. This paper compares the readability of 2021 and 2011 textbooks. The Singapore Centre for Chinese Language’s teaching resource platform and Soh’s (2000) Chinese as Second Language Readability Formula were used for the comparison of readability and analysis of differences in difficulty between different courses. It was found that differences between levels of Chinese curricula have changed in the 2021 teaching materials, with increased difficulty of Higher and Express Chinese, widened gap between Express and Normal Academic Chinese, and Basic Chinese and Chinese B put at the same difficulty level.  It was also found that the Chinese as Second Language Readability Formula can easily and objectively determine the difficulty of Chinese texts and is a practical method that textbook writers and teachers can easily apply to select texts. It is thus a meaningful tool that optimises Chinese language teaching.