Objective: To investigate the prophylactic effect of hyperensort on hypotension during subarachnoid anesthesia in cesarean section. Methods: A total of 90 full-term singleton parturients admitted to Tianjin Haihe Hospital from Jan. 2019 to Jan. 2020 were divided into an observation group and a control group with 45 cases in each group by random number table method. In the observation group, ephedrine was injected i.v. in the subarachnoid space (0.1 mg/kg), the control group underwent routine treatment. Systolic blood pressure (SBP), diastolic blood pressure (DBP), incidence of hypotension, maternal pregnancy outcome (anesthesia time, operation time, blood loss, length of hospital stay), neonatal indicators (birth weight, cord blood pH value, Apgar score) of the two groups were compared, and adverse reactions during hospitalization were counted. Results: The highest and lowest SBP values in the observation group were significantly higher than those in the control group, and the difference was statistically significant (P <0.05). The lowest DBP value in the observation group was significantly higher than that in the control group, and the difference was statistically significant (P <0.05). The incidence of hypotension in observation group was significantly lower than that in control group, and the difference was statistically significant (P <0.05). There were no significant differences in anesthesia time, operation time, blood loss and hospital stay between the two groups. Apgar score 3 min after birth in the observation group was significantly higher than that in the control group, and the difference was statistically significant (P <0.05). The pH value of cord blood in the observation group was significantly lower than that in the control group, and the difference was statistically significant (P <0.05). The cumulative dose of the observation group was (12.13±1.42)mg; the incidence of nausea and vomiting was 2.2% (1/45) in the observation group and 6.7% (3/45) in the control group, there was no statistical significance between the two groups. Conclusion: Prophylactic application of ephedrine can reduce the incidence of hypotension during subarachnoid anesthesia in cesarean section, and the outcome of mother and child is also normal, which is worthy of clin. promotion.