Molecular diagnosis is mainly the application of molecular biology methods to detect changes in the structure or expression level of genetic material in organisms to make a diagnosis. The most commonly used method of molecular diagnosis is molecular PCR diagnosis, which uses primers to specifically amplify the target gene to detect the presence or absence of endogenous or exogenous target genes, thereby providing information and decision-making for disease prevention, diagnosis and treatment According to the evidence, its main characteristics are high sensitivity, strong specificity, short diagnostic window, and qualitative and quantitative detection.