Objective To analyze the effect of esketamine on analgesia and renin angiotensin aldosterone system（RAAS）and the occurrence of postpartum depression after cesarean delivery．Methods The subjects were 96 pregnant women who underwent cesarean section in our hospital from May 2020 to June 2021,they were divided into 50 cases in the study group and 46 cases in the control group．Both groups of pregnant women were given combined spinal epidural anesthesia for cesarean section．The patients in study group were injected with esmketamine 0.2 mg/kg intravenously 5 minutes before skin incision,and those in control group were injected with the same amount of saline intravenously．The postoperative pain scores（VAS score）,plasma renin activity（PRA）,angiotensin-II（AT-II）,aldosterone（ALD）,Edinburgh Postpartum Depression Scale（EPDS）,and the occurrence of adverse effects were compared between the two groups．Results Compared with the control group,maternal VAS scores were significantly lower in the study group at all postoperative time points,and the differences were statistically significant（P<0.01）．The indexes of RAAS were significantly lower in both groups at T1,T2 and T3 time points than at T0 time point（P<0.05）;the indexes of RAAS were significantly lower in the study group at T1 and T2 time points than in the control group,and the differences were statistically significant（P<0.05）．The postoperative EPDS scores in the study group were significantly lower than those in the control group at 3 d and 6 weeks（P<0.01）．There was no difference in the overall incidence of adverse reactions between the two groups（P>0.05）．Conclusions Esketamine is effective for postoperative analgesia after cesarean section,with less effect on maternal RAAS,and can relieve maternal depressive symptoms,and has a low incidence of adverse reactions．