Objective: To explore the biological function and downstream mechanism of microRNA-21-5p (miR-21-5p) in glioma. Methods: MiRNA microarray dataset GSE41032 was downloaded,and the differentially expressed miRNAs in glioma tissues were screened using GEO2R online analysis tool. Quantitative real-time PCR was used to detect the expression of miR-21-5p in glioma tissues and cell lines. Cell viability,migration,invasion and apoptosis were detected by MTT assay, Transwell assay and flow cytometry analysis, respectively. qRT-PCR and Western blot were used to detect the mRNA and protein expression levels of photostase and tensin homologue (PTEN), human mutS homolog-2 (hMSH2) and programmed cell death 4 (PDCD4). Results: MiR-21-5p was up-regulated in glioma tissues and cells, and inhibition of miR-21-5p significantly suppressed the viability, migration and invasion of U251 cells, and promoted apoptosis; overexpression of miR-21-5p had the opposite effect. PTEN, hMSH2 and PDCD4 were identified to be downstream targets of miR-21-5p, and they were negatively regulated by miR-21-5p. Conclusion: MiR-21-5p can promotes the progression of glioma by targeting PTEN, hMSH2 and PDCD4.