The aim of this study is to investigate the effectiveness of teaching descriptive text using clustering technique on students’ writing ability for the eighth grade of SMP IT Robbani Kendal. The method used in this study is a quantitative research and the design is a experimental research. The sample of this research is the eighth grade of SMP IT Robbani Kendal. Students of VIII B class as the experimental class, whereas students of VIII A as the control class. Each class consists of 23 students. The sample technique of the study is random sampling. It based on the teachers’ recomendation. The instrument used in this research is a written test of the pre-test and post-test. The data is served by numerical and tested by the statistical formula of the t-test. Based on the calculation of the data, after teaching descriptive text using clustering technique on students’ writing ability, the mean score of the experimental class is increased. The finding of this study showed that clustering technique is effective on students’ writing ability of descriptive text. It is proved by the data that (2.800) is higher than (2,015) in the significance level of 0.05. It is considered that (null hypothesis) is rejected and (alternative hypothesis) is accepted. It is stated that there is a significant effect on teaching descriptive text using clustering technique on students’ writing ability.