Objective To compare the learning curves of femoral nerve block guided by nerve stimulator and ultrasound for residents.Methods Twenty-four residents during their rotation in department of Anesthesiology were divided into two groups:nerve stimulator learning group (group N) and ultrasound-guided learning group (group U).The study included 15 cases of femoral nerve block completed continuously by each resident physician from April 2018 to October 2018.The operating time,confidence score,operating quality and learning satisfaction of each resident in the two groups were compared.Results The operation time gradually decreased in both groups.The operating time tended to be stable after 11 exercises in N group,and 13 exercises in U group.The confidence score of doctors in the two groups increased with the number of practices.The number of successful cases of the last three operations of group N was less than that of group U (24 cases vs 32 cases),and the operation time was longer than that of group U (9.1±1.5) minutes vs 7.0±1.2 minutes),all P <0.05.Conclusions In order to achieve a more stable state,more operations were needed for residents to perform femoral nerve block anesthesia under the guidance of ultrasound,but the last three operations are better than those under the guidance of nerve stimulator.