【Ａｂｓｔｒａｃｔ】　Ｏｂｊｅｃｔｉｖｅ　To investigate the effects of dexmedetomidine （Dex） on cesarean delivery women and newborn undergoing combined spinal-epidural anesthesia.　Methods　Ninety ASA Ⅰ-Ⅱ full-term pregnancy women who underwent elective cesarean section were randomly divided into 3 groups（n=30）： control group （group A） and Dex group （group B and group C）. Dex was respectively infused intravenously at 0.5 μg/kg in group B and 1 μg/kg in group C while in group A equal volume of normal saline was infused instead of Dex. The maternal mean arterial pressure（MAP）， heart rate（HR）， pulse oxygen saturation（SpO2）， Ramsay scores of mothers were recorded at six time points： before iv（T1）， 5 min after iv（T2）， 10 min after iv（T3）， 15 min after iv（T4）， 20 min after iv（T5） and the neonate was delivered（T6）. Sensory block onset time， duration， the highest level， the time required to achieve the highest level were also recorded， as well as motor block onset time， the highest scores， the time required to achieve the highest scores. Umbilical arterial blood was obtained immediately after breaking the umbilical cord for analysis of blood gas and lactic acid. Apgar scores 1 min and 5 min after labor were recorded， and neonatal behavioral neurological assessment （NBNA） scores 2 d and 14 d after labor were evaluated.　Results　Ramsay scores were significantly higher， MAP， HR， SpO2 were lower in group C than in group A and B（P<0.05）. Sensory block onset time， duration， the highest level median， the time required to achieve the highest level of group A， group B， group C were respectively as follows： （5.5±1.9） min vs （3.9±1.5） min vs （3.9±1.6） min， （80.1±13.4） min vs （92.0±14.5） min vs （91.3±15.5） min， 5.5 （6， 4） vs 4 （4， 3） vs 4 （4， 3）， （13.2±3.2） min vs （10.4±1.9） min vs （10.2±2.5） min. The differences were statistically significant （P<0.05） compared with group A. Motor block onset time， the highest scores， the time required to achieve the highest scores of group A， group B， group C were respectively as follows： （4.2±1.7） min vs （3.3±1.4） min vs （3.1±1.2） min， （84.5±10.4） min vs （95.6±14.3） min vs （98.3±12.3） min， （16.5±5.8） min vs （13.3±2.7） min vs （12.4±2.7） min. The differences were statistically significant compare with group A（P<0.05）. There was no significant differences in umbilical arterial blood gas analysis， lactic acid， Apgar Scores and NBNA scores among the 3 groups（P>0.05）.　Conclusions　Dex can provide good sedation， shorten onset time of spinal anesthesia and extend the blocking duration with no adverse effects on Apgar scores and NBNA scores before employing combined spinal-epidural anesthesia. The effect on maternal hemodynamics was less at 0.5 μg/kg than 1 μg/kg of Dex.