The research was initiated by doing an observation to the students of SMK Negeri 1 Gunungsitoli Barat; where the students’ mark on Mekanika Teknik lesson was still low. Concerning to the problem, the researcher aimed at implementing one of the cooperative learning methods- ‘STAD’- to increase the students’ ability. The research design was Classroom Action Research. Intruments used were teacher’s and students’ observation sheet, students’ test sheet and interview. The research was conducted at the tenth grade of the first semester at SMK Negeri 1 Gunungsitoli Barat under the competence of Keahlian Bisnis Konstruksi dan Properti year 2018/2019, consisted of 9 students. The result revealed that (1) the first meeting of cycle I, the teacher’s response in the teachinglearning process achieved 60% while in the second meeting was 67%. Otherwise the students’ observation sheet showed 53% and in the second meeting was 62%. The students’ ability mean score was 46%. (2) the first meeting of cycle II revealed that the teacher’s response in the teaching-learning process achieved 87% and in the second meeting was 90%. For the students’ observation sheet, it was 84% and in the second meeting was 92%. As an impact of the increase of the teachers’ response and the students’ liveliness, the students’ ability mean score was 81,17, which was the percentage of minimum learning mastery was 100%, otherwise 0% was for incompleteness. It is said that 75% of minimum learning mastery is achievable. As a conclusion is implementing one of cooperative learning methods type ‘STAD’ can increase the students’ ability in Mekanika Teknik lesson of the tenth grade of SMK Negeri 1 Gunungsitoli Barat.