Ｏｂｊｅｃｔｉｖｅ　To observe the effects, stress response and safety of different doses of dexmedetomidine（Dex） on epidural analgesia after caesarean section.　Methods　According to different doses of the Dex， 80 cesarean section patients with ASA Ⅰ-Ⅱwere averagely divided into four groups by random number table method： A（0）， B（0.5 mg/L）， C（0.8 mg/L）, D（1.5 mg/L）， with A being the control group. Every group was separately combined with 0.15% ropivacaine and fentanyl （2 mg/L） for patient controlled epidural analgesia（PCEA）. The visual analogue scale （VAS）, drug consumption， total press numbers, effective press numbers， mean arterial pressure， heart rate， sensation， Motor block level（Bromage score）， Sedation degree（Ramsay score） at 6， 12， 24， 48 h after caesarean section and the side effect（nausea and vomiting and pruritis， shiver etc） were recorded. The date of the cortisol（Cor） and blood glucose（Glu） at preoperative and 6, 12, 24, 48 h after caesarean section was also recorded.　Results　B，C，D groups showed lower score than A group in visual analogue scale（P<0.05） and the difference between static VAS score［（1.7±0.9），（1.6±0.6）］ and dynamic VAS score［（3.3±0.7），（3.4±0.5） ］ of B and C groups had remarkable statistical significance 12 h postoperatively， but there were no significance between B and C groups（P>0.05）. At 6，12 h Cor and Glu postoperatively there was an evident statistical significance（P<0.05） between B，C groups and A group. Compared with 48 h drug consumption, total press numbers, effective press numbers, A group is significantly higher than other groups （P<0.05）， while B group and C group had no statistical significance （P>0.05）. Besides， There were no obvious abnormal in the average blood pressure and the motion function of both lower extremities. Moreover， adverse reaction rate of A group is significantly higher than other groups. In D group, 4 cases suffered from local skin numbness，1 case lethargy and 1 case bradycardia.　Conclusions　Dex significantly enhanced the effect of analgesia， decreased stress response and reduced adverse reaction rate and total drug comsunption on epidural analgesia after caesarean section. The experiment also showed concentration of dexmedetomidine in 0.5 mg/L-0.8 mg/L was same effect of epidural analgesia and the more safety with comparison of concentration of dexmedetomidine in 0.8 mg/L-1.5 mg/L.