Abstract: Objective To analyze the current quality of treatment for hospitalized cancer patients in Beijing, identify major issues in treatment practices, and propose improvements, providing a reference for enhancing China's cancer prevention and treatment system. Methods Nine hospitals in Beijing were selected for examination. Expert on-site interviews and medical record sampling were conducted. The Beijing Cancer Diagnosis and Treatment Quality Control Checklist was used to assess various aspects of anti-cancer treatment at these hospitals. Issues in hardware, management, anti-cancer drug therapy, radiation therapy, and surgical treatment during cancer treatment from January to October 2023 were analyzed. Results Among the nine hospitals, 2 (22.2%) were equipped with laminar flow rooms, and 3 (33.3%) had intravenous drug preparation centers. In terms of institutional management, 7 hospitals (77.8%) had standardized anti-cancer drug prescription authority management, 8 (88.9%) had complete emergency plans, and 5 (55.6%) had oncology specialist pharmacists. Regarding anti-cancer drug therapy, the areas with higher completion rates included pathology diagnosis support (97.6%), routine pre-treatment examinations (96.3%), discharge summaries (95.1%), adverse reaction evaluation(92.7%), and admission records (91.5%). However, the accuracy of tumor staging before treatment (70.7%) and the evaluation of therapeutic efficacy after drug treatment (76.9%) need improvement. The oncology specialty significantly outperformed the non-oncology specialty in terms of the accuracy rate of TNM staging (86.0% vs. 46.9%, P< 0.001), the completeness of informed consent forms (100% vs. 68.8%, P< 0.001), the completeness of drug indication evaluation (96.0% vs. 78.1%, P= 0.025), the completeness of admission medical history records (98.0% vs. 81.3%, P= 0.008), the rationality of drug dosage (96.0% vs. 75.0%, P= 0.005), the rationality of drug infusion time (100% vs. 62.5%, P< 0.001), and the rationality of the order of drug infusion (100% vs. 87.5%, P= 0.010). While the quality of radiation therapy was high, the subsequent evaluation of therapeutic efficacy (39.3%) requires enhancement. In surgical treatment, the preoperative pathology diagnosis support rate (78.1%) and the accuracy of tumor staging (37.5%) were relatively low, indicating issues with incomplete preoperative evaluation and the absence of multidisciplinary discussions. Conclusion There remains significant room for improvement in the quality of cancer treatment in China. It is recommended to standardize tumor staging assessment processes, strengthen entry assessments for non-oncology departments, promote the implementation of multidisciplinary treatment models, and establish a multi-department collaborative management model. Continuous monitoring of cancer diagnosis and treatment quality indicators is essential to promote ongoing improvements in cancer treatment quality.