Objective CD8 +T cells increased in the airway of patients with chronic obstructive pulmonary disease and exis -ted constantly .The aim was to investigate the role of CD 8 +T-cells in rats with chronic bronchitis ( CB) which was induced by cigarette smoking and intratracheal injection with lipopolysaccharide ( LPS) . Methods 18 health Wistar rats were radomly divided into sham smoking group(group A), CB group(group B) and N-acetylcysteine prevention group (group C).The rats in group B and group C re-ceived intratracheal injection with LPS twice and exposed to cigarette smoking for 4 weeks to induce CB model .The rats in Group C re-ceiving intragastric administration with N-acetylcysteine (NAC)(200mg/kg) before received LPS and smoking.Group A was the sham smoking group.The lung tissue of all rats were stained by HE then evaluated about pathological scores .The expression of nuclear fac-tor-κB (NF-κB), major histocompatibility complex class I (MHCI), CD8 +T cell and Vascular endothelial growth factor (VEGF) in airway were detected by immunohistochemisty which was stained by labeled streptavidin biotin method . Results The pathological scores of airway ( 10 .83 ±3 .31 ) in group B were higher than (1.17 ±2.40) in group A(P <0.05).The pathological scores of airway(4.66 ±2.25) in group C were less than (10.83 ±3.31) in group B(P <0.05).The expression of NF-κB(4.84), MHC I (2.48),CD8 +T cell(5.35)and VEGF(5.02) in airway increased in group B when compared with (1.18, 1.25, 1.33) and (1.18) in group A respectively(P <0.05).The expression of NF-κB (2.18), MHC I(1.46),CD8 +(2.35)and VEGF(2.02) in airway decreased in group C when compared with (4.84), MHC I(2.48),CD8 +T cell(5.35)and VEGF(5.02) in group B respectively (P<0.05 ). There were positive correlations between the expression of NF-κB, MHC I and CD8 +T cells in airways(r=0.670, r=0.701, respec-tively, all P<0.01).There were positive correlations between the expression of CD 8 +T cells and VEGF the pathological scores of air-ways(r=0.689, r=0.782, respectively, all P<0.01). Conclusion NAC can inhibit airway inflammation which is regulated by CD8 +T-cells and VEGF through suppressing the expression of NF -κB and MHC I.