NEAT1 was overexpressed in OS tissues, which positively correlated with tumor size, Enneking stage and distant metastasis of OS patients. The elevated level of NEAT1 was confirmed in OS cell lines including MG63 and HOS in vitro Knockdown of NEAT1 by two siRNAs induced impaired cell vitalities,promotes the apoptosis and G0/G1 arrest in two cell lines,which was associated with inhibited anti-apoptosis signals BCL-2 pathway and cell cycle-related cyclin D1 (CCND1) signals.Moreover, the tumor suppressor microRNA-34c (miR-34c) was negatively regulated and inhibited by NEAT1 in OS. Suppression of miR-34c could up-regulate the expressions of its target genes BCL-2 and CCND1 to antagonize the effects of NEAT1 knockdown. Furthermore, overexpressed NEAT1 reduced the sensitivity of cisplatin (DDP) and inhibited DDP-induced apoptosis and cell cycle arrest via miR-34c.