After the library passes the quality inspection, the library is carried out by pooling according to the effective concentration of the library and the expected amount of data. Finally, according to the sequencing read length, the corresponding type of sequencing machine is selected for sequencing. The basic principle of Sequencing is Sequencing by Synthesis. Four kinds of fluorescently labeled dNTP, DNA polymerase and connector primers were added into the sequencing flow cell for amplification. When each sequencing cluster extended complementary chain, each fluorescently labeled dNTP added could release corresponding fluorescence. The sequencer captured the fluorescence signal and converted the light signal into sequencing peak through computer software. The sequence information of the fragment to be tested is obtained.