Abstract: Objective: This paper aims to explore the role of clinical pharmacists of pain specialty in the treatment of refractory cancer pains by implanting intrathecal drug delivery systems (IDDS). Methods: A clinical pharmacist participates in a case of clinical treatment of a patient with refractory cancer pains by implanting IDDS, evaluates the nature of the patient’s pains, assists the doctor to formulate an individualized dosing plan from the aspects of analgesic drug selection, drug dose, adverse drug reactions and interactions, and closely observes the treatment effect of the patient’s pains and the concurrent symptoms. In this way, this paper puts forward reasonable suggestions for the clinical drugs, and carries out pharmaceutical care for the patient and provides medication education. Results: The patient’s pain control is satisfactory, and the drug treatment is comprehensively optimized without any serious adverse drug reactions. Conclusion: By conducting dynamic and comprehensive pain assessment on cancer pain patients, the clinical pharmacist of pain specialty participates in analgesic plan formulation and adverse reaction monitoring. Therefore, it is advised to help optimize the intrathecal analgesic medication plan from the perspective of rational medication, improve the medication compliance of patients and ensure their medication safety