The purpose of this study is to know the application of Debate Method to improve speaking skills for senior high school students of class XII -A in Ulumuddin boarding school Utenkot, Cunda - Lhokseumawe for academic years 2018 – 2019, and to know students effectivity after applicating the Debat Methode. This research is classroom action research conducted in 3 cycles. Each cycle consists of planning, action, observation / evaluation, and reflection. The subjects of this study are senior high school students of class XII-A who are 25 students and the object of this research is speaking skills. Data collection in this study are carried out by the method of observation, interviews and diagnostic tests. The data are analyzed by quantitative descriptive and statistical analysis techniques. The results showed (1) that the application of the debate Method consisted of the stages of the purpose of Debate method application in the learning process of teaching Arabic, giving titles, limiting the Debate members, making debating rooms in class, searching for information about the title of the Debate, and providing evaluation sheets activities of researchers and students in application the Debate method, (2) in the application of the Debate Method there is an increase in the percentage of speaking skills of students of class XI -A MA in terms of pronunciation, fluency, vocabulary, and sentence structure. Based on the results of the analysis in the first cycle the average student's speaking skills are obtained as much as 70% ("medium" category). Then in the second cycle students' skills improved. The average speaking skills of students are 74% ("medium" category). And in the third cycle the average skill of students are 81.4% ("high" category). Based on the results of these studies it can be concluded that the application of the debate method can improve students' speaking skills in terms of pronunciation, fluency, vocabulary, and sentence structure.