Objective:To explore the influencing factors for postoperative delirium in General Ward of Neurosurgery and evaluate the influence of serum acetylcholinesterase level in it.Methods:A retrospective study was performed. Two hundred and ninety-eight patients accepted surgery and diverted into General Ward of Neurosurgery in our hospital from January 2021 to July 2021 were chosen in our study. The 4AT delirium scoring tool was used to evaluate whether the patients had delirium, and these patients were, then, divided into non-delirium group and delirium group. The preoperative general data, history of deseases and laboratory results (serum acetylcholinesterase level) were collected. Univariate analysis and multivariate Logistic regression analysis were used to determine the independent factors affecting the occurrence of postoperative delirium, especially the relation between preoperative serum acetylcholinesterase level and postoperative delirium. Receiver operating characteristics (ROC) curve was drawn to evaluate the predictive value of serum acetylcholinesterase in postoperative delirium.Results:The incidence of postoperative delirium in 298 patients in General Ward of Neurosurgery was 24%, including 225 patients into the non-delirium group and 73 patients into the delirium group. There were significant differences between the two groups in the proportions of patients having resuscitation in anesthesia ICU, using postoperative analgesic pump and having alcoholism history, surgical duration, intraoperative bleeding, proportion of patients accepting skull base surgery, proportion of patients remaining awake 2 h after surgery, and incidence of bilateral frontal lobe pneumatosis after surgery ( P<0.05). Preoperative serum acetylcholinesterase level in delirium group ([2.35±0.49] U/mL) was significantly lower than that in non-delirium group ([2.78±0.48] U/mL, P<0.05). Preoperative serum acetylcholinesterase level ( OR=0.116, 95%CI: 0.034-0.394, P=0.001), postoperative resuscitation in anesthesia ICU ( OR=0.043, 95%CI: 0.002-0.878, P=0.041), keeping awake 2 h after surgery ( OR=7.641, 95%CI: 1.675-34.858, P=0.009), surgical duration ( OR=1.887, 95%CI: 1.192-2.987, P=0.007), intraoperative bleeding ( OR=1.010, 95%CI: 1.006-1.014, P<0.001), and skull base surgery ( OR=6.700, 95%CI: 1.907-23.547, P=0.003) were all independent influencing factors for postoperative delirium in patients in General Ward of Neurosurgery. The area under ROC curve for serum AchE level to predict the occurrence of postoperative delirium was 0.735(95%CI: 0.679-0.800, P<0.001); when the cut-off value was 2.67 U/mL, the sensitivity and specificity were 64% and 75%. Conclusions:Skull base surgery, keeping awake 2 h after surgery, long surgical duration and large amount of intraoperative bleeding can promote the occurrence of postoperative delirium; admission to anesthesia ICU after surgery can reduce the occurrence of delirium. When the preoperative serum AchE level is less than 2.67 U/mL, the possibility of postoperative delirium should be warned.