This protocol describes a multicenter, randomized, crossover non-inferiority trial (NNPO-BE) in four tertiary hospitals in China. The study compares oscillating nasal negative pressure therapy (NNPO) with oscillating positive expiratory pressure (OPEP) in patients with acute exacerbations of bronchiectasis. Airway clearance techniques (ACT) are the mainstay of treatment, but conventional methods have limitations in tolerability, staffing, and adherence. Patients receive both therapies in random order over four consecutive days. The primary outcome is sputum wet weight collected during and within 30 minutes after each treatment. Secondary outcomes include lung function, oxygen saturation, patient-reported efficacy, comfort, and adverse events. The study will evaluate the short-term efficacy and safety of NNPO versus conventional therapy in hospitalized patients.