This study aims to determine the effectiveness of Communicative Language Teaching (CLT) method in teaching learning process and English speaking ability about “introduce my self” for eleven grades of SMK Wiratama 45.2 Wonosobo. This research use a experimental design with a population of all eleventh grades students of SMK Wiratama 45.2 Wonosobo , namely XI TKR , XI TKJ and XI APH. The samples of this study are XI TKR 2 and XI TKR 3. This research used pre-test and post-test to collect data. The results show that use of CLT method is effective to improve speaking ability. In experimental class, the average pre-test score was 52 and the average post-test score was 76. While in control class, the average pre-test score was 58 and the average post-test score was 68. Based on the resukts of the analysis, it can be concluded that the use of CLT method is effective to improve students’ speaking ability for eleven grades in SMK Wiratama 45.2 Wonosobo. The implementation of the use of Communicative Language Teaching can be seen from the enthusiasm of students in applying this method on the Communicative Language Teaching is quite good. This can be inferred from the final results of the average post-test experimental class. to determine the significant differences between students who are taught by using Communicative Language Teaching method and those who are taught without using Communicative Language Teaching method.