Abstract: Objective To investigate the effects of dexmedetomidine and subanesthetic dose of ketamine on postoperative cognitive function and recovery quality in the elderly with orthopedic surgery. Methods The clinical data of 124 elderly patients undergoing orthopedic surgeries was retrospectively analyzed. According to the administration of perioperative anesthesia, they were divided into control group(dexmedetomidine group, 61 cases)and observation group(dexmedetomidine combined with subanesthetic dose of ketamine group, 63 cases). The hemodynamic parameters ［mean arterial pressure(MAP), heart rate(HR)］ before surgery, at skin peeling and extubation, cognitive function evaluated by Mini-mental State Examination(MMSE)］ before surgery and at 1 and 3 d after surgery were recorded, occurrence of postoperative cognitive dysfunction(POCD)and awakening quality indicators such as recovery time, extubation time and agitation muscle activity evaluated by Muscle Activity Scale(MAAS)score were recorded. Besides, the differences of immune status including interferon-γ(IFN-γ), interleukin-4(IL-4), IFN-γ/IL-4 before surgery and at 1 d after surgery were compared in the two groups. Results At skin peeling and extubation, the MAP and HR in the two groups were increased compared with those before surgery(P<0.05), but there were no significant differences between the two groups(P>0.05). There were no significant differences in the MMSE - scores between the two groups before surgery and at 3 d after surgery(P>0.05). At 1 d after surgery, the MMSE scores in the two groups were lower than those before surgery and at 3 d after surgery(P<0.05), and the MMSE score in the control group was lower than that in the observation group(P<0.05). The incidence rate of POCD within 1 d after surgery and MAAS score at extubation in observation group were lower, and recovery time as well as extubation time was earlier than those in control group(P<0.05). At 1d after surgery, the IFN-γ, IL-4 and IFN-γ/IL-4 levels in the two groups were higher than before surgery(P<0.05), and the observation group was higher than the control group in IFN-γ and IFN-γ/IL-4(P<0.05), and IL-4 level in the observation group was lower than that in the control group(P<0.05). Conclusion Dexmedetomidine combined with subanesthetic dose of ketamine can simultaneously improve the immune function and cognitive function of elderly patients undergoing orthopedic surgery, and it is of positive significance in improving the awakening quality of patients.