Purpose: We intended to evaluate expression and mechanisms of human microRNA 1270 (hsa-miR-1270) in papillary thyroid cancer (PTC). Methods: In PTC cell lines and human PTC tumors, hsa-miR-1270 expressions were evaluated by qRT-PCR. HsamiR-1270 was downregulated in TPC1 and K1 cells via lentiviral transduction. Its effects on PTC cancer cell proliferation, migration and in vivo transplantation were assessed, respectively. Potential targeting of hsa-miR-1270 on downstream gene, Suppressor Of Cancer Cell Invasion (SCAI), was assessed. In hsa-miR-1270-downregulated PTC cells, SCAI was further downregulated to examine its associating role in hsa-miR-1270-mediated regulation on cancer cell proliferation and migration. Results: Hsa-miR-1270 was aberrantly upregulated in PTC cell lines and human PTC tumors. In TPC1 and K1 cells, lentivirus-mediated hsa-miR-1270 downregulation suppressed cancer cell proliferation, migration and in vivo transplantation. Hsa-miR-1270 binds SCAI and inversely regulated SCAI gene expression in PTC cells. SCAI downregulation removed the suppressing effects of hsa-miR-1270 downregulation in human PTC cells. Conclusion: Hsa-miR-1270 downregulation may suppress human PTC cell development both in vitro and in vivo. The regulatory mechanism of hsa-miR-1270 in PTC may be primarily associated with SCAI.