Ｏｂｊｅｃｔｉｖｅ　To evaluate the safety and efficacy of dexmedetomidine (Dex) as an adjuvant to ropivacaine in scalp block.　Methods　Fifty patients, including 24 men and 26 women, American Society of Anesthesiologists(ASA) grade Ⅰ to Ⅲ, who were scheduled for elective craniotomy in Union Hospital from March to December 2018 were enrolled in the current study. They were randomly divided into two groups (n=25): group C and group Dex. They underwent bilateral scalp nerve block before general anesthesia induction, where 1 ml normal saline in 0.4% ropivacaine was used for group C, and 1 μg/kg Dex diluted into 1 ml normal saline in 0.4% ropivacaine was used for group Dex. Then, both groups were compared for Visual Analogue Scale (VAS) scores and Ramsay sedation scores 1, 2, 6, 12, 18 h and 24 h after craniotomy. Meanwhile, the duration of sensory block, the need for rescue analgesia, analgesic satisfaction scores and postoperative complications were recorded with 24 h after craniotomy.　Results　Compared with group C, remarkable decreased VAS scores were found in group Dex 6, 12, 18 h and 24 h after surgery (P<0.05). There were no statistical differences in Ramsay sedation scores between the two groups 6, 12, 18 h and 24 h after surgery (P>0.05). Group Dex presented markedly extended duration of sensory block and reduced need for rescue analgesia within 24 h after surgery (P<0.05). There were no statistical differences in analgesic satisfaction scores between the two groups (P>0.05). No significant difference was found in the incidence of peri-operative adverse reactions between the two groups (P>0.05).　Conclusions　The use of 1 μg/kg Dex as an adjuvant to ropivacaine for scalp block can effectively reduce VAS scores in patients after craniotomy, which provides better management of postoperative analgesia.