Abstract: microRNA(miRNA), a kind of small non-coding RNA, was highly conserved in evolution of species. During the process of biological development, miRNAs were selectively expressed at a specific time or in specific tissues. It was speculated that most genes in organisms might be regulated by miRNAs, and the same miRNA might regulate the expression of multiple genes with similar or even unrelated functions. In the current study, the characteristics of miRNA, the biosynthesis processes in animal and plant cells, the regulation mechanism of target genes and its function in organisms were reviewed. In particular, key roles of miRNAs in insect development and plant-pathogen interaction were elaborated, and the application potential of miRNA as a biological pesticide was analyzed. In addition, this study discussed target gene prediction methods using thermo dynamic stability of miRNA-mRNA complexes, sequence conservation across species, miRNA databases, expression levels and functional correlations of miRNA and mRNA, etc in detail. On this basis, the prediction and verification methods of miRNA target genes and its advantages/disadvantages were discussed in detail from the perspective of software prediction and experimental analysis. And existing research methods could not perform well in both sensitivity and accuracy, and the development and application of this field was limited due to the lack of systematic research, providing some thoughts and suggestions for miRNA-related research in the future.