Background and objectives <p>Post-traumatic hydrocephalus (PTH) is a prominent complication that arises after decompressive craniectomy(DC) for traumatic brain injury⁽¹⁾, characterized by a multifaceted pathogenesis and substantial inter-individual variability. This study aims to identify potential risk factors to provide clinical support for the diagnosis and treatment of PTH.</p> Methods <p>This study retrospectively analyzed the clinical data of 457 patients who underwent decompressive craniectomy for traumatic brain injury at the Department of Neurosurgery, Sir Run Run Shaw Hospital, between January 2015 and December 2022. Univariate analysis and Multivariable binary logistic regression were conducted to identify risk factors. The resulting model was validated using three approaches: ROC curve analysis, decision curve analysis (DCA), and goodness-of-fit tests. </p> Results <p>PTH occurred in 123 patients (26.9%). Multivariable analysis identified postoperative intracranial infection (OR = 15.296), midline shift ≥ 10 mm (OR = 195.636), effacement of the ambient cistern (OR = 25.361), subarachnoid hemorrhage (OR = 5.324) and distance between the superior margin of the bone window and the midline &lt; 2.5 cm (OR for ≥ 2.5 cm = 0.334) as independent risk factors. Firth regression confirmed midline shift as a robust predictor (OR = 95.63). Subgroup analysis based on the timing of PTH onset showed that distance between the superior margin of the bone window and the midline &lt; 2.5 cm was associated with earlier PTH onset (&lt; 3 months) (OR = 10.40). </p> Conclusion <p>Several clinical and radiological factors are independently associated with PTH after DC, with midline shift being the most significant predictor. A short distance between the superior margin of the bone window and the midline is associated with earlier onset of PTH.</p>