Objective To investigate the effect of adductor canal block（ACB）combined with patient⁃con⁃ trolled intravenous analgesia（PCIA）on postoperative depression in patients undergoing total knee arthroplasty. Methods Eighty patients undergoing total knee replacement were randomly divided into ACB plus PCIA group （Group A）and PCIA group（group B），with 40 cases in each group. Group B were given PCIA after operation， while group A was given ACB before operation additionally. The Visual Analogue Scale（VAS）score at resting and during movement were recorded at 2 h（T1），6 h（T2），12 h（T3），24 h（T4），72 h（T5）after operation. The use of remedial analgesics after operation and the incidence of nausea and vomiting were recorded. The hospital anxiety and depression scale（HADS）score was recorded before operation，1 day and 3 days after operation. Results The VAS scores at resting and during movement from T1 to T4 in group A were significantly lower than those in group B（P < 0.05）. In group A，the use of remedial analgesics and the incidence of nausea and vomiting after operation were significantly reduced（P < 0.05）. In group A，the HADS score 1 day after operation and the propor⁃ tion of patients with significant depressive symptoms（HADS⁃D ≥ 8）were significantly lower than those in group B （P < 0.05）. There was significant positive correlation between HADS score 1 day after operation and VAS score at resting and during movement from T1 to T4（P < 0.05）. There was significant positive correlation between HADS score 3 days after operation and VAS score at resting and during movement from T1 to T3（P < 0.05）. Conclusion ACB combined with PCIA is more effective than PCIA alone after total knee arthroplasty，and can reduce the occur⁃ rence of adverse emotions and promote rapid recovery of patients.