Objective To compare the effect of Dexmedetomidine and DF mixture（pethidine and droperidol mixture）and prevent adverse reactions caused by carboprost during cesarean section.Methods 60 parturients scheduled for lower-uterine cesarean section under lumbar epidural anesthesia were randomly divided into a Dexmedetomidine group（D group）and DF mixture group（DF group）,which received 0.5μg/kg Dexmedetomidine or DF mixture（pethidine 50mg+ droperidol 2.5 mg）respectively after delivery and 2 min before administration of Carboprost.Nausea,vomiting,dyspnea,facial flushing,and cardiovascular adverse events after administration of Carboprost,and OAA/S score of the mother before Carboprost administration（T0）,10 min after Carboprost administration（T1）,and right after surgery（T2）were recorded.Results Incidence of nausea,vomiting,dyspnea,and facial flushing showed no significant difference between the two groups（P>0.05）.Incidence of hypertension in the D group was significantly higher than that in DP group（P<0.05）.Incidence of tachycardia in DP group was significantly lower that in D group（P<0.05）.OAA/S score of the patients at T0 and T1 showed no significant difference between the two groups.But at T2,OAA/S score in D group was significantly higher than that in DP group（P<0.05）.Conclusion Pre-administration of low-dose Dexmedetomidine（0.5μg/kg）or half-dose DF mixture before Carboprost administration during cesarean section can significantly reduce the incidence of adverse reactions of the gastrointestinal and cardiovascular system evoked by Carboprost.