The present study focused on the characterization and genomic sequence of phage PS2 that infects Serratia marcescens clinical isolates.The morphology of phage PS2 was observed with electron microscope.The one-step growth curve,host range,and stability of PS2 were investigated.In addition,PhageDNA was extracted from the purified phage particles using a MiniBEST Viral RNA/DNA Extraction Kit.DNA sample was analyzed by digesting with restriction enzymes.The phageDNA was used for constructing the sequencing library.The library was sequenced on a MiSeqTM platform.The whole genome sequence was obtained by Velvet (version1.2.08) assembling.Phage PS2 belongs to the Myoviridaefamily.The linear,circularly permuted,167 266-bp double-stranded DNAgenome of PS2 has high similarities to T4-1ike phages.The phageDNA contains 41.7% GC and 276 ORFs.PS2 exhibited a 21-minute latent period and 70 PFU per cell at burst size when the pathogenic S.marcescens strain S2 served as a host.Further investigation suggested that PS2 is stable in a wide pH range (pH5 to pH10) and at extreme temperatures (50 ℃ and 60 ℃) after incubation alone at different pHs and different temperatures,respectively.The paper focused on the isolation and identification of a novel lytic S.marcescens phage,the biological characteristics,the whole genome sequencing and the preliminary study of bioinformatics,which laid the foundation for deeply analysis to the phage therapy of multi-drug resistant bacteria and the phagebiological information.