Objective: To observe the effect of Haemophilus influenzae colonizing in lower respiratory tract on airway inflammation and immune imbalance in asthmatic mice, and to study the signaling pathway. Methods: Thirty-two C57BL/6 wild type (WT) and 32 TLR4 gene knockout (TLR4^-/-) mice were used. The C57BL/6 mice were randomly divided into control group (NC), asthma group (AC), inoculation group (NS) and asthma inoculation group (AS), and there were 8 mice in each group. Thirty-two TLR4^-/- mice were grouped same as above. Mice in AC and AS group were sensitized and stimulated by ovalbumin (OVA) to make chronice asthma model. The Hemophilus influenzae AGAR bead was infused into the airway to prepare the airway colonization model. The levels of IL-17 and IL-10 in serum were measured by ELISA. Th17, Treg and TLR4+ cells in spleen nonocytes were isolated and detected by flow cytometry, and the association analysis among them was performed. Results: In C57BL/6 wild type mice, compared with AC, NS and NC group, IL-17, IL-17/IL-10, Th17 and TLR4⁺ cell increased, and IL-10 and Treg decreased significantly in AS group, which indicated Haemophilus influenza colonization worsen airway inflammation and led to immune imbalance. Compared with AS group of C57BL/6, IL-17, IL-17/IL-10, Th17, Th17/Treg, TLR4+ cells were decreased, and IL-10 and Treg increased in AS Group of TLR4^-/mice, which implicated Haemophilus influenza colonization in lower airway might play effect through TLR4^-/- signaling pathway. Correlation analysis showed that ratio of CD4⁺T lymphocyte with TLR4 expression was positively correlated with Th17 ratio(r=0.912, 0.723, P<0.05, respectively), while was negatively correlated with ratio of Treg cells (r=0.689, P<0.05), indicating that Haemophilus influenzae colonzing in the lower respiratory tract, may affect the balance of Th17 and Treg to influence the immune balance through TLR4. Conclusions: Haemophilus influenzae colonization in lower respiratory tract may aggravate the immune imbalance of asthmatic mice through signal transduction of TLR4, which led to the progression of asthma.