In order to realize the individualized teaching of Chinese language in primary schools, this research has developed an online Chinese reading assessment for primary schools, which aims to record the students test process and analyze the development level of students Chinese reading ability. In this paper, the item response theory (IRT) is applied to the quality analysis of the assessment in terms of measurement attributes (difficulty, discrimination, guessing), item characteristic curve, item information function and test information function. Additionally, this paper further explores the relationship between the various parameters of the items. The results show that the IRT can effectively guide the construction of the reading assessment scale, improve the discrimination degree, reduce the guessing degree, and effectively improve the quality of the item. This paper also proposes a method to find out the unreasonable options and modify items locally through project parameters and option analysis. It is expected that researchers and educators can modify the item more efficiently by quality analysis.