ObjectiveTo compare postoperative analgesic efficacy and motor function recovery between ultrasound guided adductor canal block (ACB) and Femoral nerve block (FNB) in patients after total knee arthroplasty (TKA). MethodsFrom March to April 2014, 40 patients chosen to receive TKA under general anesthesia were randomly allocated to FNB group and ACB group with 20 in each group. Opioids consumption during and after operation, pain score in rest and movement, the force of quadriceps femoris, activity of knee and complications after surgery were recorded. ResultsNo differences were found in opioids consumption during and after operation, pain score in rest and movement after operation. Patients of ACB group were superior to those of FNB group in motor function recovery. At hour 2, 4, 8, 12, 24, and 48 after operation, the force of quadriceps femoris was higher in patients of ACB group than those of FNB group (P<0.05). Activity of knee was higher in patients of ACB group than those of FNB group postoperatively. ConclusionACB and FNB have equal postoperative analgesic effect for TKA patients. But ACB has less influence on the force of quadriceps femoris than FNB. Therefore, patients of ACB group are superior to those of FNB group in motor function recovery, showing better activity of knee and early time of first straight leg raising.