Objective：To explore the efficacy and safety of dexmedetomidine in sedation and analgesia during implantation of intrathecal drug infusion system（IDDS）for patients with advanced cancer pain. Methods：A total of 40 patients with advanced cancer pain classified as ASAⅡ~Ⅲ scheduled for IDDS implantation surgery were randomly assigned to two groups：the dexmedetomidine combined with fentanyl group（the Dex group，n=20）and the single fentanyl group（the Fen group，n=20）. In the Dex group，patients were infused with dexmedetomidine at a loading dose of 0.5 μg/kg within 10 min before operation，followed by a maintenance infusion of 0.2-0.5 μg/（kg·h）until the end of surgery. Patients in the Fen group were infused with equal volume of normal saline. All patients received 1 μg/kg fentanyl intravenously 5 minutes before operation. During the operation，fentanyl was intermittently injected according to patients’ visual analogue score（VAS）scores. MAP，HR，SpO2，VAS and Ramsay scores were measured and recorded for this study at T0（after entering operation room），T1（the beginning of operation），T2-T7（operation for 15 min，30 min，45 min，60 min，75 min and 90 min），T8（the end of operation），T9（15 min after arrival at PACU）and T10（30 min after arrival at PACU）. The incidences of side effects（nausea，vomiting，respiratory depression，etc.），fentanyl consumption，time to full recovery and patient satisfaction scores were also recorded. Results：Compared with the Fen group，the MAP was significantly lower in the Dex group at T2 and T3（P < 0.05）. In the Dex group，HR was significantly lower at T2-T8，whereas SpO2 was higher at the same time points mentioned above（P < 0.05）. VAS scores were significantly lower in the Dex group compared with the Fen group at T3-T5 and T7-T10，whereas Ramsay scores were significantly higher at T1-T10（P < 0.05）. Compared with the Fen group，patients required less fentanyl consumption and acquired higher satisfaction scores in the Dex group（P < 0.05）. Conclusion：Dexmedetomidine combined with fentanyl can be safely used in patients with advanced cancer pain for IDDS implantation surgery，which can achieve better sedation and analgesic effect，less fentanyl consumption and higher satisfaction scores.