Aim To investigate the correlation of serum changes and markers of brain injury (BI) in cerebrospinal fluid (CSF) with postoperative cognitive dysfunction (POCD) in patients with cerebral aneurysmal subarachnoid haemorrhage (aSAH). Methods 120 patients diagnosed with aSAH were included. 3 months after surgery, these patients were divided into a normal cognition group and a cognitive dysfunction (CD) group relying on the Montreal Cognitive Assessment (MoCA) Scale. Results The correlations were analysed between the serological changes and the levels of BI markers, such as neurofilament-light (NF-L) protein, Ubisquitin C-terminal hydrolase L1(UCH-L1), Glial Fibrillary Acidic Protein (GFAP), and neuron specific enolase (NSE) in patients after surgery. Hunt-Hess grading standard was employed to determine the severity of aSAH in patients. The mean values of NF-L, UCH-L1, GFAP, and NSE were (8.2 ± 4.3) pg/mL, (0.7 ± 0.3) ng/mL, (2.2 ± 0.4) ng/mL, and (48.5 ± 10.9) ng/mL in patients with severe aSAH, which were remarkably higher than those in patients with mild aSAH [(3.5 ± 0.7) pg/mL, (0.5 ± 0.2) ng/mL, (1.3 ± 0.7) ng/mL, (30.7 ± 8.2) ng/mL]. The sensitivity, specificity, and accuracy of the combined prediction of four detections for POCD were 90.80%, 84.20%, and 82.80%, respectively, which were greatly higher than those of four independent predictions (p < 0.05). The combined prediction effect of the four items, with the area under the curve (AUC) of 0.938 and the 95% confidence interval (CI) of 0.851-0.926. Conclusions BI markers NF-L, UCH-L1, GFAP, and NSE could be utilized as predictors of POCD in patients with aSAH, deserving a reference value.