Background Several randomized controlled trials (RCTs) have compared the treatment of acute lung injury (ALI) with or without omega-3 fatty acids, yet the results remained inconsistent. Therefore, we attempted this meta-analysis to analyze the role of T Omega-3 fatty acids in the treatment of ALI patients.Methods We searched PubMed et al databases from inception date to Oct 31, 2019 for RCTs that compared the treatment of ALI with or without omega-3 fatty acids. Two authors independently screened the studies and extracted data from the published articles. Summary mean differences (MD) with 95% confidence intervals (CI) were calculated for each outcome by means of fixed- or random-effects model.Results Six RCTs with a total of 277 patients were identified, with 142 with omega-3 fatty acids treatment and 135 without omega-3 fatty acids treatment. Omega-3 fatty acids treatments significantly improve the PaO2 (MD =13.82, 95%CI 8.55– 19.09), PaO2/FiO2 (MD =33.47, 95% CI 24.22– 42.72), total protein (MD =2.02, 95% CI 0.43– 3.62) in ALI patients; furthermore, Omega-3 fatty acids treatments reduced the duration of mechanical ventilation (MD =-1.72, 95% CI -2.84– -0.60) and intensive care unit stay (MD =-1.29, 95% CI -2.14– -0.43) in ALI patients.Conclusions Omega-3 fatty acids can effectively improve the respiratory function and promote the recovery of ALI patients. More studies focused on the long-term efficacy and safety of omega-3 fatty acids use for ALI are needed.