This is a nationwide multicenter prospective non-interventional registry study enrolling 600 Chinese patients diagnosed with PPF over a 3-year period (9-month enrollment, 2-year follow-up, and 3 months for data analysis and publication). Eligible participants must meet the PPF criteria defined by the 2022 ATS/ERS/JRS/ALAT guidelines, while patients with IPF, no baseline chest HRCT, or refusal to sign informed consent will be excluded. The primary endpoint is the absolute change in FVC (mL) at 1- and 2-year follow-ups. The core objective is to investigate real-world disease progression in Chinese PPF patients, with secondary objectives to analyze their clinical characteristics, current treatment status, and unmet clinical needs.