Objective To investigate the efficacy of decompressive craniectomy (DC) combined with ipsilateral external ventricular drainage (iEVD) for severe traumatic brain injury (sTBI). Methods A retrospective case control study was performed on the clinical data of 54 sTBI patients admitted to the First People's Hospital of Taizhou from January 2015 to March 2018. There were 38 males and 18 females, aged 18-72 years [ (51. 8 ± 15. 4)years]. The Glasgow Coma Scale (GCS) of patients ranged from 3 to 8 points. Among 54 patients, 27 received DC treatment, including 18 males and nine females aged (50. 1 ± 2. 9)years (DC group);27 patients received DC combined with iEVD, including 18 males and nine females aged (53. 4 ± 3. 1) years (DC-iEVD group). Intracranial pressure after surgery and complications ( hydrocephalus and subdural hygroma) 2 weeks after surgery, andModified Rankin Scale (mRS) 3 months after surgery were compared between the two groups. Results All patients were followed up for 2.5-4 months [(3.0 ±0.8)months]. No significant difference was found in intracranial pressure at postoperative 12 hours and 24 hours between the two groups (P>0. 05). However, the intracranial pressure of DC-iEVD group were significantly lower than those of DC group at 36, 48, 60 and 72 hours after operation (P<0. 05). The hydrocephalus incidence 2 weeks after surgery of DC-iEVD group was 15％ (4/27), while that of DC group was 7％ (2/27)(P >0. 05). The subdural effusion incidence 2 weeks after surgery of DC-iEVD group was 19％ (5/27), while that of DC group was 44％ (12/27) (P<0. 05). According to mRS, patients with good outcome in DC-iEVD group accounted for 63％(17/27) while the ratio was 44％ (12/27) in DC group. The prognosis of DC-iEVD group was slightly better than that of DC group, but the difference was not statistically significant(P>0. 05). Conclusion For sTBI, combined use of DC and iEVD can better control intracranial pressure and reduce the occurrence of subdural effusion.