Idiopathic pulmonary fibrosis (IPF) is a highly heterogeneous and lethal pathological process with limited therapeutic options, which is the most common and severe of the idiopathic interstitial pneumonias (IIPs). During the past 20 years, the incidence of IPF increased significantly. Most of IPF patients show a median survival time of 2-3 years after diagnosis. Five-year survival rate is 30%-50%. It's difficult to diagnose in the early stage of IPF. Once the patients go to hospital, it's already in the late stage. Now there is no effective therapy except lung transplant for IPF in clinical application.