The qualified DNA samples were randomly broken into fragments with a length of about 350 bp by ultrasonic crushing. The whole library construction process was completed by terminal repair, 3'-end A addition, sequencing linker addition, purification, fragment screening, qPCR amplification and other steps, and then the effective concentration of the library was accurately quantified by QCPR method (the effective concentration of the library was more than 3 nM) to ensure the quality of the library for subsequent sequencing. The metagenomic DNA was sequenced by 2  152 bp double-ended sequencing protocol on Illumina HiSeq platform.