Abstract: Objective: To investigate the effects of bronchoalveolar lavage on the expression of Toll-like receptor 4( TLR4) in peripheral blood of patients with chronic obstructive pulmonary disease( COPD) and its clinical significance. Methods: Among 70 patients with mechanical ventilation of COPD,36 cases treated with bronchoalveolar lavage and 34 cases treated with conventional mechanical ventilation were divided into the observation group and control group,respectively. The expression of TLR4 in peripheral blood were detected by Real-time PCR,and the levels of tumor necrosis factor-( TNF-),interleukin( IL)-6 and IL-8 were measured using enzyme-linked immunosorbent assay in two groups. Results: The differences of TNF-,IL-6,IL-8 and TLR4 levels in two groups on the first day after treatment with mechanical ventilation had no statistical significance( P 0. 05). The levels of TLR4,IL-6 and IL-8 in observation group on the fifth day after treatment and the level of TNF- in observation group on the third and fifth day after treatment were significantly higher than those in control group( P 0. 01). The differences of TNF-,IL-6,IL-8 and TLR4 levels in observation group on the first,third and fifth day after treatment with mechanical ventilation combined with BAI had statistical significance( P 0. 01),the pairwise comparisons of which had statistical significance( P 0. 05 to P 0. 01). The differences of TNF-,IL-6,IL-8 and TLR4 levels in control group on the first,third and fifth day after treatment with mechanical ventilation had no statistical significance( P 0. 05). The levels of TLR4 expression and TNF-,IL-6 and IL-8 in observation group were positive correlation( P 0. 05). The differences of pulmonary infection control window time,total time of mechanical ventilation,ICU time,the rate of first offline and online again in two groups had statistical significance( P 0. 05). Conclusions: The bronchoalveolar lavage can raise the TLR4 expression in peripheral blood of patients with mechanical ventilation of COPD and increase the success rate of offline, which hints that the COPD treatment is associated with the body's natural immune.