【Abstract】 Objective To observe the effect of ultrasound-guided transversus abdominis plane block used dexmedetomidine combined with ropivacaine on prolactin level and postoperative analgesia after caesarean section.Methods Fifty ASA ⅠorⅡ patients aged 20～40 years undergoing spinal cord anesthesia in cesarean were divided into two groups randomly: group A and group B. The patient in both groups received transversus abdominis plane block in both sides under the guidance of ultrasound immediately at the end of surgery.Group B received 0.75g/kgdexmedetomidine with 0.33% ropivacaine 30ml.,0.33% ropivacaine 30ml in group A.The time for colostrums and the level of prolactin before surgery,12、24、48h postoperatively were detected,respectively;Visual analogue score(VAS) at rest and during postoperative nausea and vomiting(PONV)、respiration depression 、dizziness were observed at 6、12、24 and 48h after the operation.Results The time for colostrums was earlier in group B than group A（P<0.05）.Compared with group A,the serum level of prolactin in group B were higher at 12、24、48h after the surgery;there was no significant difference at intraoperative（P>0.05）. The VAS scores at rest were no significant difference at 6、12h（P>0.05）;however, the VAS scores were higher in group A（P<0.05）.VAS at during activity in group B was lower than that in group A at 6、12、24、48h after the operation （P<0.05）.The incidence of PONV、respiration depression 、dizziness were significantly decreased in group B compared with group A at 6、12、24、48h after the operation （P<0.05）.Conclusion Ultrasound-guided transversus abdominis plane block with 0.75g/kgdexmedetomidine combined with 0.33% ropivacaine 30ml after caesarean can promote early lactation、the maternal analgesia effect and less adverse reactions.