21st century education aims to improve students' scientific literacy skills. The results of PISA study show that the scientific literacy of Indonesian students is in low category. The low scientific literacy of students is caused by several factors in education system, both from the curriculum, teachers, and students themselves. This study aims to analyze the ability of scientific literacy of Grade X SMA in Sungai Penuh City in terms of the competency aspect of science and the level of science literacy questions. This research is a descriptive research using mixed method and using sequential explanatory design. Sample in this research were 86 students who came from three high schools with high, medium and low categories taken by cluster random sampling technique. The instrument used was a scientific literacy test item and an interview guide sheet. Data analysis technique is done by giving a score for each of students answer then described into value and category of scientific literacy achievements and analyze the interview results. Based on the study results, it is known that the average value of each scientific competency is, 22.66 for competence to explain phenomena scientifically, 47.15 for evaluating and designing scientific investigations competence, and 28.44 for the competence to interpret scientific data and evidence. Based on the question level, the highest score was obtained at level 1 questions with an average value of 46.08 and the lowest was on level 6 questions with an average value of 7.17.