Reading becomes one of the most important skills in learning English because it declared in the Holy Quran, chapter (surah) Al-Alaq regarding its importance the students need to improve their vocabulary mastery because there are some vocabularies in every part of reading. In order, the students need to build good reading habit in English because it was beneficial to improve vocabulary mastery. As the fact, it was not easy for the students to build good reading habit because they still difficult to understand the language. Then, this research was to find out the correlation between senior high school students’ reading habit and their vocabulary mastery. This research used quantitative approach with correlational design. The respondent of this research were 108 students from 150 students’ grad XI in one senior high school at Yogyakarta. The questionnaire and vocabulary test as the instruments used to measure the data. The first finding showed that senior high school students’ reading habit in English in low category because the mean value was 12.65. Then, the vocabulary mastery was in low category because the mean value was 5.16. Furthermore, the H1 or there is a correlation between reading habit in English and vocabulary mastery is accepted because the significant value was 0.019 and lower than 0.015. It means that between reading habit in English and vocabulary mastery has positive significant low correlation and reading habit is main point to improve students’ vocabulary mastery.