Abstract: OBJECTIVE To investigate the effects of berberine on the inflammation and the activation of NF-κB signal pathway in a rat model of Pseudomonas aeruginosa induced pneumonia. METHODS Total of 40 healthy adult male rats were randomly divided into 4 groups（n=10）: the control group, berb group, model group and berb+model group. P.aeruginosa was injected into the lung trachea to establish the pneumonia model in rats. The control group was given the same amount of normal saline. The berb+model group was given berberine（200 mg/kg） by oral administration 2 hours after the model was established. The berb group was given berberine（200 mg/kg） 2 hours after the same amount of normal saline was given. The white cells in bronchoalveolar lavage fluid（BALF） were counted and the levels of cytokines including TNF-α and IL-6 in the downstream of NF-κB signal pathway in BALF were measured by enzyme-linked immunosorbent assay（ELISA）. Myeloperoxidase（MPO） activity in lung tissue was measured, and the protein levels of NF-κ B signaling including NF-κB p65, p-NF-κB p65, IκBα and p-IκBα were measured. RESULTS Compared with the control group, P.aeruginosa induced pneumonia in rats significantly increased the number of white cells in BALF（P＜0.001）, which significatly increased the production of inflammatory factors such as TNF-α and IL-6 in BALF（P＜0.001）, up-regulated MPO activity（P＜0.001）, and also promoted the activation of NF-κB signaling pathway（P＜0.001）. On the contrary, berberine could reverse these change. CONCLUSION The findings suggested a therapeutic potential of berberine on P.aeruginosa induced pneumonia. The ameliorative effects on the P.aeruginosa induced inflammation might be associated with the inhibition of activation of the NF-κB signaling pathway.