Abstract： Astragalus is the dried root of Astragalus Membranaceus and Astragalus Mongolica,family leguminosae,and its chemical composition is relatively complex,with the main active ingredients in-cluding flavonoids,saponins,polysaccharides,and amino acids.In this paper,we discuss the mechanism of action and clinical application of Astragalus and its active ingredients in pulmonary diseases from the functions of anti-inflammation,anti-oxidative stress injury,anti-fibrosis,anti-lung tumour,improvement of respiratory muscle fatigue,regulation of pulmonary vascular permeability,protection of pulmonary vascular endothelial injury,improvement of pulmonary vascular remodelling,regulation of immune function,and enhancement of body resistance,with the research targets of providing references to the further research and application of Astragalus in pulmonary diseases.