MicroRNAs (miRNAs) are endogenous 16-29 nt non-coding small RNAs that were are generally found in species and typically encoded by endogenous genes. They play an important regulatory role at post-transcription level by targeting mRNA cleavage and translation repression. More and more plant miRNAs had been predicted and identified along with the development of bioinformatics and experimental techniques. At stress conditions, plant miRNAs also play a role in adaptation by up-regulating or down-regulating the miRNA expression. The biogenesis, action mode with target genes, bio-logical functions of plant miRNAs, as well as the stress-responsive miRNAs, were reviewed and the methodologies of miRNA study were also briefly summarized in this paper.