In this study, We will conduct a single center N-of-1 trials in 36 patients with stable bronchiectasis without hemoptysis and respiratory failure. These N-of-1 trials will be randomized, double-blind, crossover comparisons of individualized herbal decoction with control decoction within individual patients. Each n-of-1 trial has 3 pairs of treatment periods. The duration of each treatment period will be 4 weeks. We will compare :(1) the efficacy of syndrome differentiation(individualized decoction) with placebo, (2) the efficacy of syndrome differentiation(individualized decoction) with the same prescription minus heat-clearing Chinese herbs, in patients with stable bronchiectasis through N-of-1 trials. The primary outcome is patient self-reported symptoms(such as cough, expectoration, shortness of breath, chest pain, and fatigue) scores on a 7 point visual analogue scale. Secondary outcomes are 24-hour sputum volume and CAT（The COPD Assessment Test） scores. We use paired t test for single case. Mixed effects model taking account of "Carryover Effects" and meta-analysis will be used for a series of N-of-1 trials as a group.