Kemampuan pemecahan masalah matematis penting dimiliki siswa sebagai bagian dari penguasaan kompetensi matematika. Penelitian ini bertujuan menganalisis kemampuan pemecahan masalah matematis siswa di salah satu SMA Negeri di Mesuji Raya berdasarkan level proficiency matematis. Subjek penelitian yaitu siswa berdasarkan tingkatan kemampuan matematis tinggi, sedang, dan rendah. Penelitian menggunakan metode kualitatif dengan instrumen soal pemecahan masalah matematis dan wawancara mendalam. Analisis data meliputi reduksi, kategorisasi, interpretasi data, dan kesimpulan. Hasil penelitian menunjukkan adanya variasi signifikan dalam kemampuan siswa di setiap level proficiency matematis. Siswa dengan kemampuan matematis tinggi mampu memahami masalah, mengaitkan konsep dengan konteks nyata, dan mengevaluasi solusi dengan baik. Siswa dengan kemampuan sedang mengalami kesulitan dalam menerapkan strategi pemecahan masalah secara efektif. Siswa dengan kemampuan rendah menunjukkan kelemahan pada hampir seluruh tahapan pemecahan masalah. Mathematical problem-solving abilities are important for students to have as part of mastering mathematical competencies. This research aims to analyze students' mathematical problem-solving abilities at at one of the state high schools in Mesuji Raya based on their level of mathematical proficiency. The research subjects were students selected based on high, medium and low levels of mathematical ability. This qualitative research method uses mathematical problem-solving instruments and in-depth interviews. Data analysis consists of data reduction, data categorization, data interpretation, and drawing conclusions. The research results show that there are significant variations in students' abilities at each level of mathematical proficiency. Students with high mathematical abilities are able to understand problems, relate concepts to real contexts, and evaluate solutions well. On the other hand, students with medium ability experience difficulty in applying problem solving strategies effectively, while students with low ability show weaknesses in almost all stages of problem solving.