Inclusion Criteria:  Bronchiectasis patients in clinically stable period; Two or more chest infections in the previous year; Chest CT confirmed bronchiectasis (bronchial to arterial ratio >1). Chronic colonization of pseudomonas aeruginosa and was clinically stable in 6 months prior to the study.  Exclusion Criteria:  deterioration of illness (defined as at least 24 hours of three or more of the following symptoms: increased cough, increased sputum volume, purulent sputum, hemoptysis, increased dyspnea, increased wheezing, fever ((≥38°C) or discomfort, the attending physician agrees that antibiotic treatment is required); current smokers, or former smokers who have stopped smoking less than 1 year ago, have a history of more than 15 packets of age, or CT showed as emphysema; cystic fibrosis patients; active allergic bronchopulmonary aspergillosis; active tuberculosis patients; patients with poor asthma control; pregnant or breastfeeding women.