Metacognitive strategies are known to be important in improving reading achievement. This study investigated whether there was any significant difference on students' reading comprehension achievement score by using metacognitive strategies and investigated what metacognitive strategies implemented on students' reading comprehension achieving. All participants of this study were students in the eleventh grade of Senior High School. The data were collected by means of Reading Comprehension Test (RCT) and Metacognitive Strategy Questionnaire (MSQ). The results indicated that metacognitive strategies had positive effect on students' reading achievement. Based on eta-squared calculation the effect size for the paired-samples t-test of the experimental group was 0.48. It means that there was a large effect, with a substantial difference in the students score before and after the treatment. There were nine sub-categories of metacognitive strategies on student's reading comprehension achievement. Such as: Advance Organizer, Self-management, Comprehension Monitoring, Production Monitoring, Self-assessment, Self-evaluation, and Self-reflection. While the high implemented of metacognitive strategies in reading comprehension consisted of two sub-categories: Selective Attention and Organizational Planning. And the highest strategy use was Selective Attention, while the least strategy was Self-reflection.