The goal of this research is to find out the correlation between students’ vocabulary mastery and their reading comprehension which was analyzed from the second-grade students of SMTI Banda Aceh, 31 of 120 students were being the objects of the research. This research was a quantitative study by collecting the data from the tests. The data were analyzed by using the formulation of Pearson Product Moment Correlation Coefficient. According to the result of the analysis and statistical calculation, it is found that rxy is 0.567 and rt are 0.355. By comparing the values of rxy and rt, it can be got that rxy is bigger than rt and the statistic hypothesis states: If ro > rt significance: there is correlation and Ha accepted. If ro < rt non-signification: there is no correlation and Ha is rejected and Ho is accepted. The result of the hypothesis is rxy bigger than rt which means the alternative hypothesis is accepted. In conclusion, vocabulary mastery significantly affects the comprehension of the students reading activity and facilitate them to get the information written in English which finally can enrich their knowledge by reading a lot of books.