Abstract: The Qihai is the primary Qi of the entire body. When the Qihai is in a state of smoothness, the Qi of lung is able to achieve normalization. Conversely, when the Qihai is in a state of disharmony, the Qi is also disrupted, which can result in the onset of lung diseases. The most effective treatment approach is to employ the method of declaring and descending the Qi movement of Qihai. This method is designed to address the underlying causes of lung diseases. This paper presents a discussion of the theoretical basis and clinical application of the Xuanjiang therapy in the prevention and treatment of lung diseases in traditional Chinese medicine (TCM), based on the theory of Qihai. The theory of Qihai provides a fundamental framework for the identification and treatment of lung diseases in TCM, offering significant theoretical insights and clinical value. From the perspective of Qihai theory, this paper discusses the use of the Xuanjiang therapy in the treatment of common lung diseases. It analyzes the causes and mechanisms of these diseases in detail and proposes that Qi movement of Qihai dysfunction, Xuanjiang lung Qi treatment for cough; phlegm stays in Qihai, Xuanjiang phlegm treatment for croup; Evil heat congestion of the Qihai, Xuanjiang pus treatment for lung carbuncle; Qihai lung ligament loss of nourishment, Xuanjiang nourishing yin treatment for consumption; Qi movement of Qihai congestion, Xuanjiang regulating Qi treatment for pulmonary distension; Qihai fluid loss, Xuanjiang dispering fluid treatment for lung impotence; and Xuanjiang Bujin treatment for lung impotence. The treatment of lung impotence was identified with reference to relevant literature and clinical data, and a summary of the treatment method and efficacy was provided. It is hypothesized that the primary pathological alteration in lung diseases within the context of Chinese medicine is the dysregulation of Qi propagation and descending. The utilization of the propagation and descending method, in conjunction with the guidance of the theory of Qihai and the rational selection of prescription drugs, has the potential to effectively improve the symptoms of the disease, delay its progression, reduce the frequency of episodes and enhance the quality of life for patients. By examining the pathogenesis of Qihai disorders in various lung diseases in detail, it becomes evident that the clinical application of the Qihai theory as a guide to promote and reduce Qi, support the positive and eliminate the evil in lung diseases can fully utilize the efficacy of TCM, and provide a clinical idea for the TCM diagnosis and treatment of lung diseases and the related research.