In January 1999, Professor Wang Junjie was tasked with establishing the Department of Radiation Oncology at Peking University Third Hospital (PUTH). In April 2001, PUTH signed a cooperation agreement with Beijing Metallurgical Hospital to establish a Cancer Treatment Center, along with the Department of Radiation Oncology, with Professor Wang Junjie serving as the Director of both the Center and the Department. From 2001 to 2014, the Cancer Center conducted clinical diagnosis and treatment at both the Metallurgical Hospital and the Party School Campus of PUTH. In July 2014, the Radiation Oncology ward was relocated back to the main campus of PUTH. In 2016, the Laboratory of Radiation Oncology was established. The Department of Radiation Oncology at PUTH currently possesses the world's most advanced radiotherapy equipment, including the Varian Trilogy linear accelerator, the Elekta Axesse linear accelerator from Sweden, the Iris CyberKnife robotic radiosurgery system, the Varian Halcyon linear accelerator, Varian brachytherapy afterloaders, a full set of radioactive seed implantation surgical equipment, large-bore CT, and deep hyperthermia machines. These encompass all current treatment modalities in the field of radiation oncology, enabling the department to perform all mainstream techniques in contemporary radiation therapy. Since its establishment over 20 years ago, the Department of Radiation Oncology has been committed to disciplinary development and talent cultivation, gradually forming a well-structured talent echelon. The department currently has 74 staff members, including 4 chief physicians, 1 chief nurse, 6 associate senior title holders, and 23 intermediate title holders. The department has developed eight specialized professional groups: Minimally Invasive and Ablative Therapy, Thoracic Tumors and CyberKnife Therapy, Breast Cancer and Gynecological Tumors, Urological and Gastrointestinal Tumors, Neurological and Head & Neck Tumors, Hyperthermia and Comprehensive Therapy, Proton-Heavy Ion and Neutron Therapy, and Radiation Combined with Immuno-Targeted Therapy. Meanwhile, the medical team, physics team, therapy team, nursing team, and laboratory work collaboratively in clinical practice, achieving systematic, precise, and specialized radiation oncology care. In 2021, the department was successfully designated as a National Key Clinical Specialty, positioning it at the forefront of high-precision oncology in China with formidable disciplinary strength and clinical capabilities. Since its establishment, the Department of Radiation Oncology has achieved outstanding research accomplishments. In the past three years, it has published over 160 papers, including more than 100 SCI-indexed articles. The department has edited 9 monographs, including "Radioactive Seed Interstitial Brachytherapy for Tumors" and "Radioactive Seed Interstitial Brachytherapy for Prostate Cancer." It has undertaken multiple National Key R&D Programs of the Ministry of Science and Technology, Key Projects, General Projects, and Youth Projects of the National Natural Science Foundation of China, Key Projects of Capital Clinical Characteristic Application Research, and Postdoctoral Science Foundation projects. Professor Wang Junjie, as the primary contributor, has been awarded the Second Prize of Science and Technology Innovation by the Ministry of Education, the Third Prize of Huaxia Medical Award, the First Prize of Beijing Science and Technology Progress Award (2020), and the Science and Technology Achievement Award of the Chinese Nuclear Society (2021). He served as Chairman of the Radiation Oncology Specialty Committee of Beijing Medical Association from 2015 to 2017, and was elected Chairman of the Radiation Therapy Branch of the Chinese Medical Association in 2020. He pioneered the clinical application of radioactive seed implantation for malignant solid tumors, CT-guided techniques, and 3D-printing-assisted technologies in China, and took the lead in establishing Chinese standards and expert consensus for radioactive seed therapy. He has successively undertaken dozens of national and provincial/ministerial research projects, including major special projects of the Ministry of Science and Technology, key projects of the National Natural Science Foundation, major special projects of Capital Characteristic Research, and the Doctoral Fund of the Ministry of Education. He has supervised over 30 master's and doctoral students. He has edited more than 10 treatment standards and monographs. As corresponding author or first author, he has published over 100 SCI papers in journals including JCO (IF 50.74), Molecular Cancer (IF 41.44), Seminars in Cancer Biology (IF 17.01), J Immunother Cancer (IF 12.49), Theranostics (IF 11.6), Int J Radiat Oncol Biol Phys (IF 8.01), and Cancers (IF 6.57). He has been invited to give lectures in the United States, Japan, South Korea, Vietnam, and Mongolia on multiple occasions. Since its establishment, the Department of Radiation Oncology has placed great emphasis on academic exchange and talent development, conducting over 20 departmental academic lectures and journal club activities annually. The department has hosted two sessions of the Beijing Radiation Oncology Annual Conference, 23 sessions of the National Particle Therapy for Tumors Training Course, accepts 4 batches of visiting physicians each year, has held 6 sessions of the Comprehensive Standardized Treatment of Gynecological Tumors Training Course, and 1 session of the Urological Tumor Training Course, having trained nearly 3,000 clinical physicians from across the country. For over 20 years, the Department of Radiation Oncology at Peking University Third Hospital has consistently upheld the philosophy of innovation and development, following and leading the trends in radiation oncology. Through perseverance and dedication, it has continuously enriched its treatment modalities and improved patient care services, establishing itself as a renowned radiation therapy center in China and worldwide.