Abstract: Objective: To explore the expressions of miR-590-5p and STAT3 in osteosarcoma 143B cells,and the effects of STAT3 expression regulated by miR-590-5p on the migration and invasion of osteosarcoma 143B cells.Methods: The target pairing of miR-590-5p and STAT3 genes was predicted by bioinformatics,and identified with luciferase assay.After miR-590-5p mimics and siRNA targeting STAT3 transfecting into cells using lipofectamine 2000,the expressions of miR-590-5p and STAT3 gene were determined by real-time PCR,and the STAT3 protein was determined using Western blotting.The migration and invasion in vitro of cancer cells were detected using the wound healing assay and transwell chamber,respectively.Results: The results of MiRanda and TargetScan showed that the target pairing of miR-590-5p and STAT3 genes was good.The results of luciferase assay showed that MiR-590-5p could inhibit the expression of STAT3 mRNA.The results of real-time PCR and Western blotting showed the over-expression of miR-590-5p could down-regulated the expressions of STAT3 mRNA and protein.The migration and invasion of 143B cells were suppressed after transfecting miR-590-5p mimics.Conclusions: MiR-590-5p can inhibit the migration and invasion of osteosarcoma 143B cells by negative regulating the STAT3 expression.