Objective: Low back pain is the most common musculoskeletal condition with a high prevalence. There was no sufficient evidence to recommend that aquatic exercise was potentially beneficial to patients with low back pain. The aim of this study was to systematically analyze all evidence available in the literature about effectiveness of the aquatic exercise. Design: A comprehensive search of PubMed, the Cochrane Library, Embase, and Cumulative Index to Nursing and Allied Health was conducted from their inceptions to November 2016 for randomized controlled trials, which concerned the therapeutic aquatic exercise for low back pain. The results were expressed in terms of standardized mean difference and the corresponding 95% confidence interval. Results: Eight trials involving 331 patients were included in the meta-analysis, and the results showed a relief of pain (standardized mean difference = -0.65, 95% confidence interval = -1.16 to -0.14) and physical function (standardized mean difference = 0.63, 95% confidence interval = 0.17 to 1.09) after aquatic exercise. However, there was no significant effectiveness with regard to general mental health in aquatic group (standardized mean difference = 0.46; 95% confidence interval = -0.22 to 1.15). Conclusions: Aquatic exercise can statistically significantly reduce pain and increase physical function in patients with low back pain. Further high-quality investigations on a larger scale are required to confirm the results.