1. The disease is often asymptomatic at the beginning, and even when the disease has progressed considerably, there are still no obvious symptoms, but is discovered by chest X-ray or chest CT during physical examination or other diseases. The main symptom is shortness of breath or shortness of breath, which many patients describe as a feeling of “breathlessness”. 2. Many patients ignore occasional shortness of breath, thinking that it is only due to old age or fatness. However, when the disease progresses and lung damage becomes severe, shortness of breath can occur after light activities such as bathing, dressing, and talking on the phone. 3.Other symptoms include frequent dry cough, and some people have flu symptoms such as fatigue, weight loss, and muscle and joint pain. 4. The disease varies from person to person. Some people have a slow progression of the disease that lasts for months or years, while others have a rapid progression; others have a stable course for a period of time that is less predictable.