Objective To observe the clinical effect of total knee arthroplasty without tourniquet under controlled hypotension combined with femoral nerve block.Methods From January 2016 to may 2018, 149 TKA patients who met the inclusion criteria were randomly divided into control group (74 cases) were treated with combined spinal and epidural anesthesia + tourniquet, and 75 patients in the observation group were treated with laryngeal mask general anesthesia + femoral nerve block without tourniquet. The total blood loss, preoperative and intraoperative blood pressure, Visual Analogue Scale(VAS), Montreal Cognitive Asesment (MoCA), and postoperative complications were compared between the two groups.Results ①There was no significant difference between the two groups in gender, gender, age, k-l grading, ASA grading,complications (P>0.05). ②The amount of recessive blood loss 48h after operation in the control group was significantly higher than that in the observation group, the difference was statistically significant (P<0.01). However, there was no significant difference in total blood loss (P>0.05). ③VAS and HSS of the observation group at 24h and 48h after operation were better than that of the control group, the difference was statistically significant (P<0.05). ④There was no significant difference in postoperative MoCA between the two groups (P>0.05). ⑤The incidence of delirium between the two groups was not statistically significant (P>0.05). The incidence of hypotension, femoral pain and nerve injury in the control group was significantly higher than that in the observation group,the difference was statistically significant (P<0.01). However, there was no significant difference between limb swelling and deep vein thrombosis (P>0.05).Conclusion Controlled hypotension combined with femoral nerve block without tourniquet technique could reduce perioperative blood loss, avoid complications caused by tourniquet, ensure surgical safety and improve patients' surgical experience with TKA.