Biological particle research combining microfluidic has been applied in cell classification, counting, etc. With the breakthrough of exosomes in cancer monitoring, drug delivery, etc., more and more researchers apply microfluidic technology to the study exosomes detection. In this paper, a method based on microfluidic technology is proposed to detect fluorescence. The detection system are design and build which is consist of optical system and detection platform. In the system, labeling technology and microfluidic technology are used to distinguish exosomes by using the specific identification of fluorescent labels to achieve exosome counting. The experimental results shows that the method and the system can effectively achieve accurate quantification of exosomes.