In order to analyze the expression of miR-484 in breast cancer tissues and cells, and its mecha-nism in breast cancer cell proliferation, metastasis and autophagy, the differentially expressed microRNAs (miRNAs) in breast cancer tissues were analyzed using GEO database, and the expression of miR-484 was detected by real-time fluorescence quantitative PCR in clinical breast cancer tissues and their paired para-cancerous tissues. The effects of miR-484 on the proliferation, metastasis and autophagy of MCF-7 breast cancer cells were detected by the miR-484 mimic and inhibitor. Then, the target gene of miR-484 was pre-dicted and verified, the Sorbin and SH3 domain-containing protein 2 (SORBS2) overexpression vector was con-structed to detect the effects of SORBS2 on the proliferation, metastasis and autophagy of MCF-7 cells. Fi-nally, the protein contents of mitogen-activated extracellular signal-regulated kinase (MEK)/p-MEK and ex-tracellular signal-regulated kinase (ERK)/p-ERK in MCF-7 cells under the regulation of miR-484 were an-alyzed by Western-blot. The results showed that miR-484 was highly expressed in breast cancer tissues and cells, and improved the proliferation, migration, invasion of breast cancer cells and reduced their autophagy ability. Meanwhile, miR-484 could down-regulate SORBS2 and activate MEK/ERK pathway to participate in the occurrence and development of breast cancer.