Objective: To investigate the effects of miR-670-5p on the proliferation, migration and invasion of lung cancer cells, further to analyze its mechanisms of regulating WW domain oxidoreductase gene (WWOX). Methods: From January 2016 to October 2017, 28 cases of lung cancer tissues and corresponding adjacent tissues were collected. And the expressions of miR-670-5p in lung cancer tissues and adjacent tissues were detected by RT-qPCR. Lung cancer cells A549 were divided into anti-miR-NC group (transfected with anti-miR-NC), anti-miR-670-5p group (transfected with anti-miR-670-5p), and anti-miR-670-5p+ si-NC group (transfected with anti-miR-670-5p and si-NC), anti-miR-670-5p+si-WWOX group (transfected with anti-miR-670-5p and si-WWOX). After 48 hours of transfection, RT-qPCR or Western Blot were used to detect the transfection effects. Cell viability was detected by using CCK-8 method; cell migration and invasion were detected by using Transwell assay; Western blot was used to analyze the expression levels of P21, E-cadherin and MMP-2 protein. The dual luciferase reporter gene assay and Western blot were applied to verify the targeting relationship between miR-670-5p and WWOX. Results: The expression level of miR-670-5p in lung cancer tissues was significantly higher than that in adjacent tissues (P<0.05). Inhibition of miR-670-5p decreased MMP-2 protein expression (P<0.05), increased P21 and E-cadherin expressions (P<0.05), and inhibited proliferation, migration and invasion of A549 cells (P<0.05). WWOX was a target gene of miR-670-5p, and miR-670-5p negatively regulated WWOX expression. Inhibition of WWOX partially reversed the effect of anti-miR-670-5p on proliferation, migration and invasion of A549 cells (P<0.05). Conclusion: miR-670-5p promotes proliferation, migration and invasion of lung cancer cells by targeting WWOX.