Objective: To establish the quality evaluation criteria for out-patient medical records of cancer pain and evaluate the effect of its application. Methods: The evaluation criterion was established based on Delphi method for out-patient medical records of cancer pain in the Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University. Firstly, the weight of each evaluation indicator was calculated by the method of Attribute Hierarchical Model in combination with technique for order preference by similarity to solution (AHM-TOPSIS), and out-patient medical records of 50 cancer pain patients (group A, 150 records) received in June 2020 were assessed comprehensively. Secondly, the relative closeness (Ci value) between the writing quality and the ideal solution was calculated, as well as the proportion of evaluation indicators which were lack of standardization. Thirdly, the corresponding countermeasures were adapted based on the results of assessment. Finally, another 50 medical records (156 records) received in October 2021 were re-evaluated by the same method, and the differences of quality of medical record and proportion of each evaluation indicator which was lack of standardization before and after the intervention were compared. Results: A specific criterion which contained integrity of materials required for the medical records, documents of the complaints and medical history of cancer pain, description of the previous medical treatment for cancer pain, regular assessment of cancer pain and its' document, quantitative assessment and its' document, comprehensive assessment and its' document, dynamic assessment and its' document, reasonable of pain medication, reasonable of the drug usage and dosage, reasonable adjustment of the drug variety or dosage, prevention of adverse reactions of analgesic drugs and its' document, evaluation and management of adverse reactions of analgesic drugs and its' document (12 indicators) was established to evaluate the out-patient medical records of cancer pain. The proportion of medical records which Ci≥0.6 was 62.0% (93/150) in group A before the intervention. It was increased to 84.6% (132/156) in group B after the intervention and the difference was statistically significant (P<0.001). Furthermore, the proportions of comprehensive assessment of cancer pain which were lack of standardization, prevention of adverse reaction, quantitative evaluation and dynamic assessment of cancer pain accounted for a higher level, which was 64.0% (96/150), 55.3% (83/150), 54.7% (93/150) and 52.7% (79/150) respectively in group A before the intervention. However, proportions of such records were decreased to 50.6% (79/156), 35.9% (56/156), 32.1% (50/156) and 39.7% (62/156) respectively in group B after the intervention and the differences were statistically significant (all P<0.05). Conclusions: A specific quality evaluation criterion is established based on Delphi method and AHM-TOPSIS for the out-patient medical records of cancer pain. The quality of medical records has been improved in a certain level after adapting comprehensive evaluation and intervention on the out-patient medical records of cancer pain.