【Abstract】 Objective To determine the minimum local anesthetic concentration of ropivacalne for ultrasound-guided phrenic nerve block in the treatments of central hiccup. Methods In this experiment, sequential experimental method was used to select patients with hiccup after the operation of cerebral hemorrhage. The starting concentration of ropivacaine was 0.25%, and the ratio between adjacent concentrations was 1.3.All patients located the superficial phrenic nerve on the left anterior scalene muscle by ultrasound,and injected the predetermined concentration of ropiacaine 4ml.After twenty minutes, by observing the symptom of all patients to identity whether the injection works or not. If the first one is effective, the next one will decrease by one concentration gradient. If the block was not effective, then the same lateral phrenic nerve block was used to be used for 4ml of lidocaine, and the nest one we will increased one concentration gradient of ropivacaine. If the hiccups did not end, the routine drug treatment will be used, at the same time, with the approval of the patients’ family, after eight hours,we will take the right phrenic nerve block, and this study does not include these patients, the next patients continue to use the current concentration ropivacaine. The effective subjects were included in effective group （group A）, the lidocaine supplement was included in invalid group (group B). Record the drug concentration and blocking effect.ED50 and 95% confidence intervals are calculated according to Dixon and Brownlee methods. Results the minimum local anesthetic concentration of ropivacalne for ultrasound-guided phrenic nerve block in the treatments of central hiccup was 0.299%, and the 95% confidence interval was (0.267%~0.335%) . Conclusion the minimum effective concentration of ropivacaine in the treatment of central hiccup was 0.299%.