Olimpiade Sains Nasional bidang Matematika tingkat SMA merupakan kompetisi bergengsi bagi siswa SMA/MA di seluruh Indonesia yang memerlukan strategi dan teknik penyelesaian soal-soal yang cenderung tidak standar, pemahaman konsep yang mendalam, dan ide kreatif. Melalui kegiatan PDWM ULM Tahun 2022, tim dosen Program Studi Matematika FMIPA ULM sebagai pelaksana dan MGMP Matematika SMA HST sebagai mitra bekerja sama menyelenggarakan kegiatan pelatihan Olimpiade Sains Nasional bidang Matematika bagi anggota MGMP Matematika SMA Kabupaten Hulu Sungai Tengah. Kegiatan ini bertujuan untuk menambah pengetahuan dan meningkatkan kemampuan anggota MGMP Matematika SMA HST agar dapat melaksanakan pembinaan Olimpiade Sains Nasional bidang Matematika bagi siswa di sekolah masing-masing. Metode yang digunakan dalam kegiatan ini adalah ceramah, diskusi, dan latihan mandiri. Kegiatan dilaksanakan selama dua hari, yaitu hari pertama yang berlangsung secara offline di sekretariat MGMP Matematika SMA HST dan hari kedua yang berlangsung secara online. Hasil evaluasi kegiatan melalui pree-test dan post-test menunjukkan adanya peningkatan signifikan dari pengetahuan dan kemampuan peserta, dengan rata-rata nilai hasil test dari peserta meningkat sebesar 41 poin pada post-test dibandingkan pada pree-test. Maksimum perubahan nilai dari pree test ke post-test adalah 90 poin, sedangkan minimum perubahan nilai dari pree test ke post-test adalah 5 poin. Melalui survey di akhir kegiatan, peserta menyampaikan harapan agar kegiatan pengabdian ini dapat berlanjut, diadakan secara berkala, dan dilaksanakan full offline.The National Science Olympiad in Mathematics at the Senior High School level is a prestigious competition for high school students throughout Indonesia who require strategies and techniques for solving questions that tend to be non-standard, in-depth understanding of concepts and creative ideas. Through the PDWM ULM 2022 program, a team of lecturers from the Program Studi Matematika FMIPA ULM as implementers and the association of MGMP Matematika SMA in Hulu Sungai Tengah Regency as partners collaborated in organizing training for the National Science Olympiad in Mathematics for members of the association. This activity aims to increase knowledge and improve the members' ability so that they can coach the National Science Olympiad in Mathematics for students in their respective schools. The methods used in this activity are lectures, discussions, and independent exercises. The activity was carried out for two days, the first day, which took offline at the MGMP Matematika SMA secretariat, and the second day, which took online. The results of the evaluation of activities through the pre-test and post-test showed a significant increase in the knowledge and abilities of the participants, with the average test score of the participants increasing by 41 points in the post-test compared to the pre-test. The maximum change in value from the pre-test to the post-test is 90 points, while the minimum change in value from the pre-test to the post-test is 5 points. Through a survey at the end of the activity, participants expressed their hope that this training could continue, be held regularly, and be carried out fully offline.