design: Qualified DNA samples were detected and large fragments of DNA were broken into small fragments with a main band of 150-250bp using the ultrasound method Covaris; Then use T4 DNA Polymerase, Klenow DNAPolymerase, and T4 PNK to repair the sticky end formed by the interruption into a flat end. Then, by connecting the 3 ends and adding a base "A", a special junction with a base "T" at the 3 ends can be made. PCR technology is used to amplify DNA fragments with connectors at both ends; Mix the prepared library with hybridization reagents, blocking agents, and SureSelect capture probe libraries for reaction. Finally, introduce the index through PCR reaction.