Polyglutamine (Poly Q) diseases are a group of neurodegenerative disorders, caused by the formation of PolyQ mutants due to trinucleotide repeats expansion in coding regions of disease-causing genes, which eventually lead to selective neuronal degeneration and death with unclarified pathogenesis. As a new type of genetic regulatory factor, microRNA (miRNA) plays an important role in modulating gene expression in eukaryote. During the recent years, more attention was paid to roles and related mechanism of miRNA involving in neurodegenerative disease, especially PolyQ diseases. This review is focused on research progress in roles of miRNA in the pathogenesis of PolyQ diseases.