: Academic supervision applied the principal of course very effective, because it can provide support, guidance and coaching to teachers to enable them to work better in guiding learners and be able to improve its performance in improving learning in schools. The research objective was to determine the effectiveness of the implementation of academic supervision by principals in improving teacher performance, through: (1) academic supervision program; (2) The academic supervision and (3) evaluation of the implementation of academic supervision. This study used a qualitative approach with descriptive methods. Data was collected through interviews, observation, and documentation. Subjects were principals, supervisors and teachers at SMK Negeri 1 Meulaboh. The research found that:(1) The academic supervision principals compiled refer to the identification of the problems faced by teachers based on the results of monitoring the previous year as the assessment, coaching and helping the difficulties teachers, and SWOT analysis, then poured into a program Plan Supervisory Academic (PSA) according to the needs of teachers; (2) The implementation of academic supervision by school principals is done in three stages: a preliminary survey prior to supervise academic, classroom visits to determine the course of learning, and reviewing the results of the class visits and provide appropriate solutions in overcoming problems that dihdapi teacher; and (3) exercising their evaluation of academic supervision by the principal, includes evaluation of the job description and evaluation of documentary evidence, by means of direct view of the evidence that the task has been undertaken by teachers and then provide input if there are errors or deficiencies. Expected principals to be able to direct and supervise the performance of teachers, especially through the program, implementation and evaluation of effective supervision and efficiency, so that student performance can be improved.