MicroRNAs are a class of endogenous, non-coding small RNA, 18~24 nucleotides in length, that mediate the post-transcriptional regulation of gene expression. The high conservation, time-dependent and tissue specificity of microRNAs make it possible for forensic body fluid identification, individual age estimation, estimation of postmortem interval, toxicity analysis, and analysis of the cause of death. However, the limitation of the quantity of identified microRNAs and the uncertainty of the research methods also limit the application microRNA in forensic science from theoretical research to practical application.