Objective To investigate the risk factors of epidural fluid collection(EFC)after cranioplasty in patients with traumatic brain injury(TBI).Methods A total of 97 TBI patients who underwent cranioplasty at Yancheng No.1 People's Hospital and Binhai County People's Hospital in Jiangsu Province from January 2020 to December 2021 were enrolled.Multiple logistic regression analysis was used to explore the independent risk factors for EFC after cranioplasty in TBI patients.Results According to the occurrence of secondary EFC,the patients were divided into EFC group(n=30)and non-EFC group(n=67).Univariate analysis showed that the proportions of patients with midline displacement>5 mm,skull defect>80 cm2,severe depression at the defect site,dural calcification,dural defect,and epidural air accumulation in the EFC group were significantly higher than those in the non-EFC group(P<0.05).Multivariate logistic regression analysis showed that midline displacement>5 mm,skull defect>80 cm2,severe depression at the defect site,dural calcification,and epidural gas accumulation were independent risk factors for EFC in TBI patients after cranioplasty(P<0.05).Conclusion The secondary EFC in TBI patients after cranioplasty is related to midline displacement distance,skull defect area and degree of depression,dural calcification,and epidural gas accumulation.In clinical practice,it is necessary to fully evaluate imaging data and strengthen surgical management to reduce the risks of secondary EFC and improve prognosis.