PCR stands for Polymerase Chain Reaction, which is mainly used to make DNA amplification for viral, genetic testing, etc. PCR is the abbreviation of Polymerase-Chain-Reaction. It is mainly used to amplify the DNA content by denaturing the DNA at high temperature in vitro, revert it at low temperature, and extend it under the action of specific temperature, primers, and so on. The use of PCR technology to amplify the DNA after its detection can be applied to detect the presence of a certain virus in the body, or to detect the presence of a certain gene mutation, such as the quantitative detection of hepatitis B virus DNA to guide the treatment, the new Coronavirus detection, detection of malignant tumors, molecular typing, and diagnosis of thalassemia and so on. PCR is a technological breakthrough in research at the genetic level and is widely used in biology, medicine and other fields, as well as in a variety of clinical examinations.