Many students got low score in Semantic and Pragmatic course. They complained that the textbook used in the course is difficult to understand. It is possible to consider that there is a correlation between the students’ bad scores and the readability of the textbook. In previous research, it was found that suitable level of readability and reading skills are important consideration to reach maximum learning gain. Because of that, it becomes important to measure readability level, the factors which influencing readability level and the best way to use the textbook. This research was a descriptive quantitative research. The sample of this research was 3 pages from 3 chapters of the textbook, chapter 9, 10, and 11 chosen randomly from each chapter. The instruments were a written questionnaire, an online readability measurement website, and notes during interview. The findings show that the readability level measured by students and readability formula was difficult. The most influencing factors in determining readability level were interest and vocabulary difficulty. The best way to use the textbook was using one single textbook, editting by put some notes on the page, then presenting it in a lecture form by the lecturer.