Abstract: OBJECTIV To establish a reliable model of Klebsiella pneumoniae bloodstream infection, so as to provide a reliable experimental model for the study of early diagnosis of bacterial bloodstream infection. METHODS K. pneumoniae ATCC700603 was selected as experimental strain. Different concentrations of bacterial suspension were injected into mice via tail vein, and the LD50 was calculated by Karber method and 1/2LD50 was used as the injection concentration. The general condition, body weight changes, blood culture, molecular biological test and HE staining were observed to comprehensively evaluate the model, and verify the modeling effect. RESULTS The LD50 was 1.11×10⁹ CFU/ml, when the bacterial fluid was infected after 1 hour, and the mice's activity was decreased. The weight before infection was (33.60±1.21)g, 1 day after the injection, the weight decreased to (28.86±1.42)g, and there were significant differences compared with that of control group (P<0.05), and returned to normal level after 7 days, which was(33.17±1.72)g. White blood cells in normal mice was (1.42±0.66)×10^9/L, after 3 hours of injection of the bacteria, it increased to (2.52±1.01)×10⁹/L, and increased to(3.08±0.85)×10⁹/L after 6 hours, and there were significant differences compared with control group (P<0.05). White blood cells increased to (6.88±3.11)×10⁹/L after 2 days, and there had no significant decline 7 days later. The results of whole blood culture showed that the blood culture results were positive in the first 2 days. The virulence factor PCR results showed that the pathogenic bacteria of the bloodstream in mice were K. pneumoniae.After 1 daysof injection, the mice were infiltrated with obvious exudation, edema and leukocyte infiltration. The lung structure was gradual recovery after 2 days, and liver recovery rate was slower than the lung. CONCLUSION A bloodstream infection model is successfully established, which provides a reliable animal model for the early diagnosis of bloodstream infection and the differential diagnosis of different pathogenic bacteria infection.