Objective: Our objective is to compare the efficacy and safety of the combination of dexmedetomidine andmidazolam with dexmedetomidine alone in the sedation during spinal anesthesia. Methods: 180 patients admittedin our hospital between April, 2015-April, 2017 were included and divided into the observation group and controlgroup for prospective controlled analysis. There were 90 cases in either group. The patients in the observationgroup received intravenous injection of dexmedetomidine and midazolam before disinfection, and the patients inthe control group only received intravenous injection of dexmedetomidine. The changes of onset time of sensoryand motor block, hemodynamics changes during anesthesia, Observer’s assessment of alertness/sedation scale(OAA/S) score, anxiety visual analogue/anxiety questionnaire (AVA/SAI) score and brain bispectral index (BIS)were compared, the anesthetic adverse reactions were compared and the efficacy and safety of two regimens werecompared. Results: The onset time of sensory block reaching the highest plane and the onset time of motor blockreaching Grade 3 in the observation group were shorter than the control group, which were statistically significant(P 0.05).Conclusion: Compared with dexmedetomidine, the combination of dexmedetomidine and midazolam can ensurethe safety of anesthesia and better anesthetic efficacy. However, the early stage heart rate during anesthesia isobviously decreased, thus the hemodynamics monitoring is important.