Vocabulary is an important element in learning English; it is the first step for the students if they want to achieve their goal of learning English skills. Learning English particularly vocabulary is very important for supporting the ability of speaking, listening, writing and reading. This research aims to describe students’ vocabulary ability of the eleventh-grade students of SMA Negeri 2 Martapura in the Academic year 2018/2019.

This study is a descriptive quantitative study. The population is 7 classes which are consist of 203 students who are taken by using cluster random sampling.  The instrument is a multiple-choice consist of 40 items, arranged based on the syllabus, lesson plan, and material books currently used at the school. The result of the test is then calculated and categorized to determine the level of students’ English achievement KKM of the school. 

Based on the result of this research, showed that the students’ vocabulary achievement in English, 27 students did not achieve the standard score of KKM. There are 6 students achieve who gain “good” category for the standard KKM in SMA Negeri 2 Martapura, from a total of 33 students. It can be concluded that the English vocabulary mastery is “poor” categories, which means that vocabulary mastery of the Eleventh Grade Students of SMA Negeri 2 Martapura in a low average level for achievement English lessons in mastering vocabulary that should mastered by students. It is suggested for the teacher and students to evaluate their way of teaching and learning English to improve the students’ vocabulary ability.