Abstract: An investigation was conducted on two patients in the intensive care unit （ICU） from whom Bacillus licheniformis was isolated in blood and cerebrospinal fluid, aiming to explore the causes and transmission routes of infection. The findings are intended to provide a reference for clinical infection prevention and control and offer a scientific basis for preventing similar infections. Both patients were male individuals and were admitted due to craniocerebral injuries. After admission, they received nasogastric administration of B. licheniformis preparation diarrhea. Within 1-8 days thereafter, they developed symptoms of infection, including high fever, chills and neck stiffness. B. licheniformis was subsequently cultured and identified from their blood and cerebrospinal fluid samples. By means of epidemiological investigation, a total of 25 environmental specimens were collected. B. licheniformis was detected in six of these, yielding a detection rate of 24.00%. Standardized protocols for the preparation of live bacterial drugs are currently lacking. It is recommended that such preparations should not be performed near the patient's bedside. Following the procedure, the surfaces of the preparation platform should be disinfected thoroughly. It is necessary to formulate corresponding standards for use of B. licheniformis for preparations.