Abstract:miRNAs are approximately 22-nucleotide endogenesis noncoding regulated RNAs in eukaryotes that have phosphate group at 5＇end and hydroxy group at 3＇end, which attract extensive attention in recent years. Scientists are now on the threshold of a better understanding how miRNAs works, miRNAs plays an important role in controlling plant development, florescence time, metabolism, response to stress, etc. Plant miRNAs are known to repress gene expression post-transcriptionally, mainly by guiding mRNA cleavage but also by attenuating the translation of target transcripts. In addition, it has been shown that plant miRNAs can also act at the transcriptional level by directing the methylation of target chromosomal loci. This paper reviews recent researches on the function and mechaism of plant microRNA.