This study was divided into two parts. The first part was a dose escalation study: a open label dose escalation design was used to evaluate the safety, tolerance and pharmacokinetic characteristics of ZSP1603 in IPF patients. The second part was a randomized double-blind placebo-controlled design was used to preliminatively investigate the efficacy and safety of ZSP1603 in the treatment of IPF at the target dose.

Inclusion Criteria:

• IPF diagnosed, according to 2018 American Thoracic Society (ATS), European Respiratory Society (ERS), Japanese Respiratory Society (JRS), Latin American Thoracic Association (ALAT) IPF guideline for diagnosis and management;
• Dlco (corrected for Hb): 30%-79% predicted of normal;
• FVC>= 50% predicted of normal;

Exclusion Criteria:

• FEV1/FVC< 0.7;
• PaO2 in resting state without oxygen inhalation < 50mmHg;
• Subjects who were likely to be lung transplant recipients or expected to survive less than 1 year during the study period as assessed by the investigator;
• Poorly controlled cardiovascular and cerebrovascular diseases;
• Patients who had used nidanib, pirfenidone, interferon, n-acetylcysteine, azathioprine, cyclophosphamide, cyclosporine, prednisone > 15mg/ day (or equivalent dose of other glucocorticoids) within 4 weeks before enrollment; Those who had used Chinese herbal medicine or acupuncture treatment within 1 week before enrollment;

The trial has two parts, a part 1 and a part 2, in part 1 will be unblinded