Background: Mounting researches have established that long-chain non-coding RNA (lncRNA) and microRNA (miRNA) occupy an essential position in osteosarcoma development. The present study attempted to explicate the functional role and mechanism of LINC00485 and miR-361-5p in regulating the osteosarcoma progression.Methods: RT-PCR was employed to measure LINC00485 expression in osteosarcoma tissues and adjacent healthy tissues. Moreover, the correlation between LINC00485 expression and the clinicopathological indexes was analyzed. Further, the LINC00485 low-expressed cell model was constructed, and the CCK8 assay was employed to measure cell proliferation, followed by the flow cytometry in apoptosis testing. Besides, Transwell assay was utilized to detect cell migration and invasion ability, and Western blot examined the alternations of epithelial mesenchymal transition (EMT) marker molecules (E-cadherin and Vimentin). Furthermore, bioinformatics analysis was taken advantage of predicting the downstream molecular targets of LINC00485. RT-PCR and Western blot were carried out respectively to estimate the expression variations of miR-361-5p and Twist1. Dual luciferase activity assay and RNA co-precipitation (RIP) assay were conducted to verify the targeting relationship between LINC00485 and miR-361-5p, miR-361-5p and Twist1.Results: In comparison with normal adjacent tissues, the LINC00485 expression in cancer tissues was profoundly up-regulated. LINC00485 low expression greatly attenuated proliferation, migration, invasion, and EMT in osteosarcoma cells, while enhancing apoptosis. Bioinformatics analysis claimed that miR-361-5p was a sponge miRNA for LINC00485, targeting the Twist1 expression. Further gain- and loss-experiments declared that miR-361-5p limited the osteosarcoma development by inhibiting osteosarcoma cell proliferation, metastasis and promoting apoptosis.Conclusions: LINC00485 acted as an oncogene in the osteosarcoma tumorigenesis by modulating the miR-361-5p/Twist1 axis.