25ml sewage water sample was mixed, centrifuge at 10,000rpm for 30 minutes. The supernatant was added NaCl to 0.5mol/L and mix with 10% PEG6000 at 4degreeC overnight; The solution was centrifuged at 8,000rpm for 30 minutes, and the precipitate obtained was enriched virus.  Genomic DNA extraction kit was used to obtain genomic DNA. The library was constructed directly by DNA-Seq library constructiong protocol.