寻求高效稳定的分子生物学方法对人类生物性体液进行鉴定，是法医物证学的发展方向，而miRNA具有保守性和组织特异性，可用于体液性质鉴定。本研究以中国汉族的血液、精液、唾液、阴道分泌液和月经血等5种体液的大量群体样本为对象，改进体液斑痕的RNA提取方法，利用miRNA基因芯片筛选，确定具有鉴定意义的miRNA位点。通过定量PCR，获得位点的△Ct值（目标基因与内参基因的循环阈值的差值）。通过这些基础研究可以建立：1.基于2种特定位点的△Ct值的组合，构建二维组合鉴定系统；2.以特定位点的△Ct值构建进化树，构建进化树鉴定系统。利用两种系统的联合应用，对斑痕检材和混合检材进行特异性鉴定，可以解决法医相关性体液的性质鉴定。

Looking for a sufficiently effective and stable molecular genetics-based methods will show a director for the future human fluid identification in forensic science. microRNA, whose profiling of both conservative and tissue-specific characteristics, should be developed as a marker for the future fluid identification. Our research will take a large number of samples from Chinese Han ethic group as object of study, which including drying marks of forensically relevant biological fluids-blood, semen, saliva, vaginal secretions, and menstrual blood. Meanwhile, improved biological fluids RNA extraction method and miRNA gene chip were used to check the miRNA marker with identification significance. Relevant miRNAs were amplified and examined by RT-PCR technology. Then the data of △Ct values was gathered statistics (intersection between an amplification curve and a threshold line). On the one hand, the △Ct values were used to create two-dimensional (2D) scatter plots to identification of biological fluids, named two-dimensional miRNA body fluid identification assays. On the other hand, the △Ct values were analyzed by the phylogenetic software and phylogenetic trees were constructed by the neighbor-joining (NJ) method, which were used for identification of biological fluids. Combined use above two systems can specifically identify either fluid stain or mixture stain and may provide a promising solution to biological fluids identification for forensic casework.