Objective：To investigate the relationship between transforming growth factor β1（TGFβ1） signaling pathway and respiratory tract infection induced inflammation and to explore the effects of TGFβ1 on immunological function of respiratory system. Methods：BACB/C mice fulfilling grade Ⅱ clean animal criteria were artificially infected with pseudomonas aeruginosa while TGFβ1 was blocked with LY364947（4-[3-（2-pyridinyl）-1H-pyrazol-4-yl]-quinoline）. Inflammation reactions of the infected mice and pathologi－cal changes of pulmonary tissue were histochemically evaluated when TGFβ1 was blocked and unblocked respectively. CD4 and CD8 levels were tested through Western blot. Results：Blocking of TGFβ1 obviously blunted the phosphorylation of p38（10% lower than the control levels），significantly intensified the inflammation reaction and increased the CD4 levels but didn’t affect CD8 levels. Conclusions：TGFβ1 has inhibitory effect on respiratory tract infection induced inflammation and TGFβ1 blockers may enhance the immune regulation of respiratory tract infection.