Chronic obstructive pulmonary disease，asthma and cystic fibrosis are distinct respiratory diseases that share features such as the obstruction of small airways and acute exacerbations.Secretory immunoglobulin A （sIgA）acts as a first⁃line mucosal protective barrier against inhaled particles and pathogens. sIgA mediates immune rejection and promotes clearance of pathogens from the airway surface by inhibiting adhesion of pathogens to the epithelium. sIgA is the main component of local mucosal immunity. The specific immune mechanism of sIgA in chronic airway diseases is still unclear. This article reviews the role of sIgA in chronic airway diseases.