MicroRNAs are a class of small non-coding RNA molecules that play crucial roles in the initiation and progression of lung cancer. This study was undertaken to investigate the expression and roles of miR-186 in lung cancer. Ectopic expression experiments demonstrated that miR-186 functions as a tumor suppressor. Bioinformatic predictions, a luciferase reporter assay, and protein expression analysis suggested that miR-186 could inhibit the protein levels of SIRT6, a purported tumor suppressor gene. Collectively, our results indicated that miR-186 could inhibit lung cancer progression through targeting SIRT6 and that miR-186 may be a therapeutic target for lung cancer.