Abstrak: Tujuan penelitian adalah dengan menerapkan Metode Brain Stirming untuk meningkatkan hasil belajar siswa. Jenis penelitian adalah Penelitian Tindakan Kelas, subyek dari penelitian ini adalah siswa kelas XI Administrasi Perkantoran sebanyak 31 siswa. Instrumen penelitian yang digunakan adalah tes evaluasi hasil belajar dan lembar observasi. Berdasarkan hasil analisa data diperoleh hasil ketuntasan klasikal siswa pada siklus I sebesar 64,5% sedangkan pada siklus II diperoleh hasil ketuntasan klasikal siswa sebesar 90,3%. Dengan demikian dapat disimpulkan bahwa penerapan Metode Brain Storming dapat meningkatkan hasil belajar matematika siswa pada materi Barisan dan Deret.Abstract:  The purpose of the study is to apply the Brain Stirming Method to improve student learning outcomes. This type of research is Classroom Action Research, the subject of this study were students of class XI Office Administration as many as 31 students. The research instrument used was the learning outcome evaluation test and observation sheet. Based on the results of data analysis, the results of classical completeness of students in the first cycle were 64.5%, while in the second cycle the results of classical completeness of students were 90.3%. Thus it can be concluded that the application of the Brain Storming Method can improve students' mathematics learning outcomes in the Sequence and Series material.