Data mining with clustering techniques is applied in many different areas of life. In choosing a training major of students of the Faculty of Information Technology, Hanoi Open University, most students choose based on feelings and personal preferences, but there is no information channel to support and advise students to choose according to their ability. Therefore, in this paper, the authors propose to apply the technique of clustering students by major based on the score groups of specific subjects of each major. The authors research and experiment with data clustering algorithms as K-Means. The grouping results are a suggestion to help students of the Faculty of Information Technology, Hanoi Open University have a basis to choose the right major for themselves.