To observe Xingnaojing′s effect on postoperative cognitive function in elderly patients with lower limbs orthopedic operation, and to discuss its influence on PI3K/AKT signal pathway in the cerebrospinal fluid. Methods:A total of 90 cases of elderly patients with lower limbs orthopedics ASA Ⅰ ~ Ⅱ grade in our hospital during August 2015 and January 2016, were included into the study. According to the random principle, they were divided into observation group and control group. Cognitive function levels of the patients were assessed by postoperative recovery Physician Quality Reporting System (PQRS) the new cognitive evaluation system on one day before the surgery, and 3 d and 7 d after the surgery. The PI3K, AKT, pAKT, Bcl, and Bax concentration changes in cerebrospinal fluid were detected by western blotting in the following time points:the finished time of the subarachnoid puncture catheter (T0), the time when inserting a laryngeal mask (T1), 6 h(T2), 24 h(T3), 48 h (T4) after the operation. Results:1) According to PQRS score and MMSE score of postoperative cognitive function in the patients, the scores of the two groups reduced, the changes of control group were more obviously than the observation group, MMSE scores got back to normal in both of the two groups 7 d after operation, while the PQRS scores showed that there were 14 cases (40%) in the control group, while 10 cases (28%) in the observation group; while MMSE scores showed that there were 12 cases (34 %) in the control group, while 8 cases (22%) in the observation group, the result of PQRS scores significantly higher than MMSE scores.3) Western blotting results showed that the concentration of PI3K, pAKT, Bcl decreased in the two groups on time points of T1, T2, T3, and T4 compared with the T0, while the Bax levels rose. The iconic protein concentration change trend of every time point of the control group was more obviously than the observation group, the differences were statistically significant (P<0.05). Conclusion:Xingnaojing can improve the postoperative cognitive function in elderly patients with lower limbs orthopedic surgery, the mechanism may be related to the mediation on iconic protein expression levels of PI3K/AKT signal pathway.