Abstract: 40 sows with endometritis and 15 sows with non-endometritis were selected and butchered in slaughter house.Mucus samples of uterine horn and uterine cervix were collected from the sows and inoculated into the culture medium.All the bacteria were purified and identified by automated bacterial identification and antibiotics susceptibility test system(ATB).Pathogenicity of each identified strains were determined by challenge intra-peritoneally to white mouse.The results show that from 40 sows with endometritis,70 isolates were determined,among them,47 isolates were in uterine cervix and 23 isolates were in uterine horn respectively.The positive rate was 100%.2 isolates were determined in uterine cervix of one of 15 sows with non-endometritis.The positive rate was 6.67%.Among the 72 isolates,16 strains were identified.The main strains were Escherichia coli,Pseudomonas aeruginosa,Pseudomonas putida and A.hydrophila and only Pseudomonas aeruginosa and A.hydrophila showed pathogenic effect in white mice.Antibiotics susceptibility test on the isolated strains of P.aeruginosa and A.hydrophila exhibited that they had strong resistance to 28 antibiotics.The results indicated that high culling rate of sows are related to endometritis.Environmental bacteria are main pathogenic bacteria of endotremitis conditionally,which have resistance to antibiotics mainly used in clinical practice.