Reading activities is one of a lot of activities in the classroom. The reading text also to be source that needed in the reading activities. A good reading texts is suitable and easy to understanding by the student based on their level. So that the objective of this study was to analyze the readability of reading texts found in the English textbook published by Viva Pakarindo for X grade of senior high school. the researcher choose these books because of the books are used in several of schools. To get the data in this study, researcher was chosen descriptive qualitative method. The data were compiled through documentation and observation on analysis of readability level of the texts by using Flesch Reading Ease Formula and COCA word register-based. The finding of this research, there are 12 texts found from book semester 1 and semester and semester 2. The result of the research based on Flech Reading Ease Formula, there are 2 texts are identified on easy level, 2 texts on Fairly easy level, 2 texts on standard level, a text on fairly difficult level and 5 text on difficult level. the average of the score is not appropiate to X students level, because readability level range score 30 – 50. So that the style of the reading texts is difficult (collage students). In addition, Based on COCA Corpus Text Analysis, almost a half of entire the words in the texts, are categorized on High Frequency, and the rest of word divided into Mid Frequency, Low Frequency, and unidentified Frequency.