PCR, Polymerase Chain Reaction, is a method for enzymatic synthesis of specific DNA fragments in vitro. It consists of high temperature denaturation, low temperature annealing (renaturation) and suitable temperature extension. The cycle is carried out, and the target DNA can be rapidly amplified. It has the characteristics of high specificity, high sensitivity, simple operation and time saving. Thermal cycler is the device for rapid amplification of genes. Based on Peltier technology, it realizes the rapid, accurate and automatic circulation of reagent temperature, thus realizing the full automation of the PCR process. It can be used not only in basic research such as gene isolation, cloning and nucleic acid sequencing, but also in clinical diagnosis of diseases.