Background: It remains unclear whether nutritional support can reduce the mortality and infection rate of patients with traumatic brain injury (TBI), improve their gastrointestinal function, and shorten the length of stay in the intensive care unit (ICU). The purpose of this study is to evaluate the effect of nutritional support on the clinical outcome of TBI patients. Methods: A computer search was conducted of the PubMed, Cochrane Library, Embase, Wanfang, and China National Knowledge Infrastructure (CNKI) databases for randomized controlled trials investigating the impact of nutritional support on the clinical outcomes of patients with TBI. The search included the period from the establishment of the database to July 2021. Two researchers independently screened the literature, extracted the data, and evaluated the risk of bias in the included studies. RevMan 5.3 statistical software (Cochrane Collaboration) was used to analyze the effect size, and a funnel plot was used to detect publication bias.Results: Seven articles reporting on 260 patients receiving nutritional support therapy compared with 252 standard nutrition control patients were included in the study. Meta-analysis showed that there was no significant difference in mortality between the nutritional support and standard nutrition treatments (RR =0.74; 95% CI: 0.34-1.60; P=0.44). However, there were significant differences in total serum protein levels