【Abstract】 Objective To investigate the optimal dose of levoupivacaine for subarachnoid block anesthesia in cesarean section. Methods Sixtythree women underwent elective lower uterine segment cesarean section in our hospital, ASA I ~ II, were divided into three groups by random number table method, 21 cases in each group. The three groups were given subarachnoid block anesthesia (lumbar anesthesia) at L23 or L34 puncture space. Group A was given 10mg of 05% levoupivacaine. Group B was given 125mg of 05% levoupivacaine. Group C was given 15mg of 05% levoupivacaine. The highest block plane and time to block plane of the three groups were recorded. The incidence rates of incomplete analgesia, incomplete muscle relaxation, dragging reactions and complications were also recorded. The mean arterial pressure (MAP) and heart rate (HR) were statistically analyzed before anesthesia (T0), after 1min (T1), 5min (T2), 10min (T3), 15min (T4) and 30min (T5) of anesthesia. Results The highest block plane of group C and group B was higher than that of group A, and the time to block plane was shorter than that of group A (P＜005), but there was no significant difference between group B and group C (P＞005). There was no significant difference among the three groups in HR at different time points (P＞005). Compared with T0, MAP were decreased in the three groups at T3 and T4, and the decrease in group C was more significant than that in group A and group B (P＜005) but there was no significant difference between group A and group B (P＞005). The incidence rates of incomplete analgesia, incomplete muscle relaxation and dragging reactions in group A were slightly higher than those in group B and group C, but there were no significant differences among the three groups (P＞005). There were no significant differences among the three groups in the incidence rates of nausea and vomiting, bradycardia and respiratory depression (P＞005); The incidence of hypotension in group C (3810%) was higher than that in group A (952%) (P＜005). Conclusion 125mg of 5% levoupivacaine for subarachnoid space block anesthesia can obtain ideal anesthetic effect, and maintain hemodynamic stability during operation.