[Objective]To isolate and identify bacteria in the uterus of postpartum healthy cows and cows with uterine infection,to gain insight into the species of pathogenic bacteria in the uterus of postpartum cows,and to explore the main pathogenic factors of uterine infection in cows.[Methods]The uterine contents of each test cow were collected,inoculated in different media, isolated and cultured at 37 ℃ for 24~48 h,and identified by microscopic examination according to different types of bacterial staining.[Results]171 strains were obtained,mainly Escherichia coli,Staphylococcus aureus,Klebsiella and Bacillus cereus. Escherichia coli accounted for the highest percentage of 23.98%,and the gram staining results showed more negative bacteria,mostly in the form of mixed infections. The results of detection rate showed that the highest percentage of Escherichia coli was 36.67% in the uterus of postpartum healthy cows.The overall detection situation showed that the detection rates of pathogenic bacteria at the early,middle and late postpartum periods were 100%,87.5% and 60%,respectively.The highest percentage of pathogenic bacteria in the uterus of cows with uterine infections in the early and middle postpartum period was E. coli（100% and 60%）,and the highest percentage of pathogenic bacteria in the late postpartum period was Bacillus cereus（60%）.The detection rate of pathogenic bacteria was 100% regardless of the early,middle and late postpartum period.[Conclusion]After inflammation of the uterus in heifers,pathogenic bacteria grew and multiplied in large numbers,intensifying the inflammatory response and promoting the process of endometritis.