Objective:To assess the effects of not monitoring gastric residual volume compared to the routine monitoring gastric residual volume on the risk of ventilator-associated pneumonia.Methods:A systematic literature search of PubMed, EMBASE, Cochrane Library, CNKI, CBM and WanFang Database was conducted from inception up to January 2019.Two independent reviewers screened potentially eligible articles, selected eligible studies and abstracted pertinent data. Relative risk ( RR), weighted mean difference ( MD), and 95% confidence interval (95% CI) were calculated and heterogeneity was assessed with the I2test. Results:Four studies with a total of 785 patients were included in this meta-analysis. No monitoring gastric residual volume did not significantly increase the incidence of ventilator-associated pneumonia ( RR=1.30, 95% CI 0.78-2.16, P=0.32), compared with monitoring gastric residual volume. However, the incidence of vomiting in the no monitoring gastric residual volume group is higher ( RR=1.52, 95% CI 1.20-1.91, P=0.000 4). Not monitoring gastric residual volume decreased the rate of feeding intolerance in critically ill patients ( RR=0.61, 95% CI 0.51-0.72, P<0.01).There were no differences in the duration of mechanical ventilation ( MD=0.39, 95% CI -0.70-1.47, P=0.49) and ICU length of stay ( MD=-0.19, 95% CI -1.55--1.16, P=0.78). Conclusion:The absence of monitoring gastric residual volume did not increase the risk of ventilator-associated pneumonia in critically patient with mechanical ventilation. Gastric residual volume monitoring can not be used as a maker to prevent aspiration and to assess feeding intolerance. We still need to conduct large-scale,well-desighed clinical trials to verify whether gastric residual volume monitoring can be eliminated.