It is elusive that whether that Mediterranean diet helps prevent gestational diabetes. This meta-analysis aims to study the efficacy of Mediterranean diet for gestational diabetes mellitus.We have systematically searched PubMed, EMbase, Web of science, EBSCO and Cochrane library databases, and included randomized controlled trials (RCTs) that reported the effect of Mediterranean diet on gestational diabetes.We included five eligible RCTs in this meta-analysis. Compared with control intervention for pregnant women, Mediterranean diet could substantially decrease the incidence of gestational diabetes mellitus (OR = 0.64; 95% CI = 0.51 to 0.79; p < 0.0001), HOMA-IR (MD = -0.29; 95% CI = -0.50 to -0.09; p = 0.004), insulin treatment (OR = 0.39; 95% CI = 0.22 to 0.68; p = 0.0009) and gestational weight gain (MD = -0.74; 95% CI = -1.21 to -0.28; p = 0.002), but demonstrated no obvious impact on the admission of neonatal unit (OR = 0.75; 95% CI = 0.47 to 1.20; p = 0.24).Mediterranean diet can effectively prevent gestational diabetes mellitus.