Objective To study the effects of different carbon dioxide pneumoperitoneum pressure and time on abdominal cavity infection bacteria of peritonitis in rats, including bacteria growth and bacterial translocation. Methods Sixty Sprague Dawley rats were injected with Eseherichia coli into the abdominal cavity to establish models of intra-abdominal infection. To give 3 types of pneumoperitoneum pressure for the experimental group: 15 mm Hg (1 mm Hg=0.133 kPa) for high pressure group, 5 mm Hg for low pressure group, and blank control group for no-pneumoperitoneum. To give 2 types of experimental period: 1 h and 3 h. These 60 Sprague Dawley rats were randomly divided intomoperi 6 groups by random number table. They were treated by different pneumoperitoneum pressure and time. All rats were killed at the end of the carbon-dioxide pneumo-peritoneum experiment. Peritoneal lavage fluids and portal vein blood were taken for microbiological examinations and culture. The endotoxin content in portal vein blood was detected too. Results ① Bacteria content: bacteria counts of different pneumoperitoneum pressure groups were obviously different (F=9.02, P=0.020), bacteria counts of different experimental period groups were obviously different (F=8.47, P=0.003), the effect of time was different in different pneumoperitoneum pressure groups (F=8.07, P=0.020). ② Bacterial translocation: Bacterial translocation occurred in all 6 groups. Blood culture positive rates were similar between 1 h group and 3 h group at 3 types of pneumoperitoneum pressure groups (P>0.05). The positive rate of blood culture in high pneumoperitoneum group was significantly higher compared with the no-pneumoperitoneum group (P<0.05). ③ The endotoxin content: the endotoxin content of different pneumoperitoneum pressure groups were obviously different (F=14.70, P<0.01), the endotoxin content in plasma increased obviously in high pressure group compared with low pressure group (P=0.018) and no-pneumoperitoneum group (P<0.01), the endotoxin content in plasma increased obviously in low pressure group compared with no-pneumoperitoneum group (P=0.005). The endotoxin content of different experimental period groups were obviously different (F=148.90, P<0.01), the endotoxin content in plasma increased obviously in 3 h group compared with 1 h group. There were no significant difference in the effect of time with different pneumoperitoneum pressure groups (F=0.14, P=0.874). Conclusion CO2pneumoperitoneum promoted intestinal bacterial endotoxin and bacterial translocation in peritonitis of rats, which increased with the pressure and time.