Objective To identify the reasons and treatment strategies of epidural fluid collection (EFC) secondary to cranioplasty in patients with traumatic brain injury after decompressive craniectomy.Methods From June 2013 to July 2017,a retrospective analysis was performed on clinical data of 150 patients with traumatic brain injury after decompressive craniectomy in our hospital.A total of 47 patients experienced EFC following cranioplasty and 103 not.Risk factors of EFC after cranioplasty were analyzed by multiple factor Logistic regression.Results For the 47 EFC patients,32 patients had no obvious clinical symptoms and EFC was absorbed gradually through conservative therapy;15 patients had clinical symptoms,such as mental deterioration,headache,or limb weakness.EFC disappeared through vacuation in 4 patients and subcutaneous drainage in 11.The proportions of patients with skull defect＞80 cm2,dural defect and dural calcification in patients with EFC were significantly higher as compared with those without EFC (P＜0.05).Multiple factor Logistic regression analysis showed that skull defect＞80 cm2 and dural mater calcification were independent risk factors for EFC after cranioplasty.Conclusions Patients with large skull defect＞80 cm2 and dural calcification are prone to have EFC after cranioplasty.Careful evaluation of imaging data,good surgical skills and strengthening postoperative management can reduce incidence of EFC after cranioplasty.