OBJECTIVE: To analyze the effectiveness of resistance exercise in the treatment of knee osteoarthritis on pain, stiffness, and physical function. DESIGN: Systematic review and meta-analysis of randomized controlled trials. DATA SOURCES: PubMed, Embase, Cochrane Central Register of Controlled Trials, the Web of Science, and Chinese Biomedical Literature Database were searched from the date of inception to August 2015. METHODS: Trials comparing effects of resistance exercise intervention with either non-intervention or psycho-educational intervention were selected by two reviewers independently. The risk of bias was assessed and studies with similar outcomes were pooled using a fixed or random effects model. RESULTS: Data from 17 randomized clinical trials including 1705 patients were integrated. The main source of methodological bias in the selected studies was lack of double blinding. The meta-analysis results suggested that resistance exercise training relieved pain (standard mean difference [SMD]: -0.43; 95% confidence interval [CI]: -0.57 to -0.29; P < 0.001), alleviated stiffness (SMD: -0.31; 95%: CI -0.56 to -0.05; P = 0.02), and improved physical function (SMD -0.53; 95% CI: -0.70 to -0.37; P < 0.001). CONCLUSION: Resistance exercise is beneficial in terms of reducing pain, alleviating stiffness, and improving physical function in patients with knee osteoarthritis.