The objective of this research is to find out the improvement of students speaking ability through small group discussion. The researcher applied quasiexperimental method. The population of this research is the second year students of SMK Negeri 1 Sinjai. The researcher used total sampling technique, where two classes were taken as sample, class of 2 AK 1 consisting of 20 students as the experimental group, and class of 2 AK 2 with 20 students as a control class. The findings of the study showed that small group discussion activated the students. The result of data analysis shows that t-test value is greater than t-table value (4.81 > 2.042) at level of significance (p) = .05 with degree of freedom (df) = 19. It means that there is a significant difference of speaking skill between two groups and it indicates that null hypothesis (H0) is rejected and alternative hypothesis (H1) is accepted. It is also supported by the observation checklist analysis that shows the students’ progress from each treatment. Therefore, it can be concluded that the use of small group discussion can improve the students’ speaking skill.