Propidium monoazide（PMA）was a kind of photoreactive DNA-binding dye with extremely high affinity for DNA. PMA could enter into the dead or membrane-damaged microorganisms，then insert into DNA structure，and following photolysis stimulated by visible light，bind to DNA to produce covalent crosslinking reaction. PCR amplification of DNA could be inhibited by the products. Based on the above characteristics，PMA-PCR technology could be used to identify living bacteria，fungi，viruses and other microorganisms. In practice，the detection results by PMA-PCR could be affected by sample turbidity，the ratio of dead and living microorganisms，PMA concentration，conditions of dark processing（temperature，dark processing time），exposure conditions（light source，light processing time），treatment method for samples，the amplification length of target genes and other factors. PMA-PCR，with wide prospects of application，had been used in animal and plant disease prevention and control，foodsafety，public health and other areas.