Abstract： Objective To understand epidemiological characteristics of Haemophilus influenzae (Hi) infection in hospitalized children with lower respiratory tract infection (LRTI) in west Sichuan China.Method The multicenter prospective cross-sectional design was used;four hospitals in west Sichuan China were chosen as research field,sputum bacterial culture was done and biological typing,PCR identification and drug sensitivity test of Hi epidemic strains were carried out among 0-17y hospitalized patients with LRTI in four hospitals located in west Sichuan China.Result Totally 5 748 cases with LRTI in four hospitals were investigated in west Sichuan from Nov.2013 to April 2014 and the rate of sputum culture was 46.96％ (2 699/5 748).The total pathogenic bacteria positive rate of sputum culture was 43.53％ (1 175/ 2 699),and 279 Haemophilus influenzae (Hi) strain in 272 cases were isolated,the Hi positive rate was 10.08％ (272/2 699).All the strains (100％) were non-typeable Haemophilus influenzae (NTHi) indentified by PCR.The main biotype of 279 strains was type Ⅰ with 39.07％ (109/279) and type Ⅳ with 50.90％ (142/279);272 cases were enrolled in this survey,12.50％ (34/272) had broncheolitis,the rest of lower respiratory infection was 87.50 ％ (238/272),and 2.57％ (7/272) was neonatal pneumonia,2.21％ (6/272)was pneumonia complicated with sepsis;in four hospitals the overall positive rate of Hi in inpatients with lower respiratory infection was 10.21％,28.96％,4.80％,10.21％ (x2 =112.561,P =0.000) and the positive rate of Hi inpatients with broncheolitis was 1 1.92％,20.93％,4.76％,and 66.67％ (Fisher exact probability P =0.001),with the rest lower respiratory infection was 9.96％,30.90％,4.81％,9.85 ％ (x2 =108.876,P =0.000);2.87％ (8/279) bacterial strains of β-lactamase-nonproducing-ampicillin-intermediary (BLNAI) distributed in four hospitals,and 1.79％ (5/ 279) bacterial strains of β-lactamase-nonproducing-ampicillin-resistant (BLNAR),0.72％ (2/279) bacterial strains of β-lactamase-positive amoxicillin-clavulanate-resistance (BLPACR) were found in two hospitals respectively.Conclusion All the Hi isolated from sputum were non-typeable among 0-17y inpatients with LRTI and the main biotype were type Ⅰ and type Ⅳ in west Sichuan China.Much attention should be paid to BLNAR and BLPACR strains found in the west Sichuan region.