This paper introduces some ways available in the literature of the West to determine the difficulty level of the texts in language textbooks by quantitative analysis. The author attempts to apply these ways to treat Chinese textbooks. First, he suggests that, as Chinese is a language with peculiarities that make it different from other languages, the following factors be incorporated to determine the difficulty level of a Chinese text: the number of new words, proportion of most frequently used words, the number of grammar items, complexity and length of sentences, the number of functional items and the correlation between the arrangement and communication of the students, register styles and, finally, the background and cultural knowledge. He then puts his suggestion to practice by analyzing difficulty level of a number of Chinese textbooks.