Objective To study the postoperative delirium in predicting dementia in elderly patients with femoral neck frac‐ture and provide prevention advises for postoperative delirium .Methods 120 elderly patients with femoral neck fracture were in‐cluded .All patients were tested normal by Clinical Dementia Rating (CDR) preoperative .Basic imformation and postoperative deliri‐um in predicting dementia were recored in detail .After one year of follow up ,all patients were tested by CDR again and divided into dementia group and without dementia group .Results There were 40 patients (33 .3% ) with delirium postoperative with dementia 1 week after operation;there were 16 patients got 0 .5 -3 .0 CDR score after one year follow up (40 .0% ) .There were 80 patients (66 .7% ) did not experience delirium postoperative 1 week after operation ,and 4 patients (5 .0% ) with dementia got CDR score higher than zero after one year folloew up;the difference was statistically significant (P<0 .05) .Single factor analyse showed that there were close correlation between age ,introverted ,level of education < 6 years ,diabetes mellitus ,delirium ,LDL‐C level and de‐mentia (P<0 .05) .Multiple factors showed that age ,diabetes history and delirium were the independent risk factors of dementia in elderly patients with femoral neck fracture (P<0 .05) .ROC curve showed that the AUC area of postoperative delirium in predic‐ting dementia in elderly patients with femoral neck fracture was 0 .878 .Conclusion In elderly patients without the history of de‐mentia ,age ,diabetes history and delirium after hip fracture surgery are the major predictor of dementia within half years .