Abstract: Objective　To investigate the positive rate, karyotype and target antigen of antineutrophil cytoplasmic antibody (ANCA) in patients with pulmonary fibrosis (PF) and its relationship with common clinical indexes. Methods　A total of 302 patients diagnosed with PF and detected by ANCA at the same time were collected. Among them, 72 ANCA-positive patients presenting with PF were selected as the ANCA-positive PF group, and 72 ANCA-negative patients presenting with PF (n=230) were selected as the ANCA-negative PF group according to the random number table method. Twenty-five ANCA-positive patients without PF were selected as the ANCA-positive non-PF group. Twenty healthy subjects were selected as the healthy control group. Karyotype and target antigen of ANCA, data of laboratory indicators related to inflammation, coagulation - fibrinolysis, immune function and renal function were analyzed. Results　ANCA positive PF patients accounted for 23.84% of PF patients in the same period. In the ANCA positive PF group, the positive proportion of pANCA was more than that of cANCA, and the positive proportion of target antigen myeloperoxidase (MPO) was more than that of protease 3(PR3). C-reactive protein (CRP) was significantly higher in the ANCA positive PF group than that in the ANCA negative PF group. ESR, CRP, procalcitonin (PCT), D-dimer and fibrinogen (FIB) were significantly higher in the ANCA positive PF group, the ANCA negative PF group and the ANCA positive non PF group than those in the healthy control group (P＜0.008). C3 was significantly lower in the ANCA positive PF group and the ANCA positive non PF group than that in the healthy control group and the ANCA negative PF group, and serum creatinine (SCR) was significantly higher in the ANCA positive non PF group than that in the ANCA negative PF group (P＜0.008). Conclusion　The possibility of antineutrophil cytoplasmic antibodies associated vasculitis should be considered when diagnosing PF, and attention should be paid to changes of ESR, CRP, PCT, D-Dimer, FIB, C3 and Scr indicators.