Abstract： Objective:To identify the differential expression of Peroxiredoxin 4 (PRDX4) in alveolar macrophages (AMs) from patients with silicosis in different phases using Western blot.Methods:From June 2017 to June 2018, Twelve pneumoconiosis patients in the pneumoconiosis Department of Beidaihe Sanitarium were selected by random sampling. A msong them, there were 4 groups, that was lung with dust, silicosis with grade one, silicosis with grade two, silicosis with grade three. There were 3 persons in each group, a total of 12. AMs was obtained by filtration and centrifugation. The intracellular protein was extracted and PRDX4 was detected by using Western blot method.Results:It results showed that PRDX4 was expressed in AMs in 4 groups; with the increase of fibrosis, the average relative expression of PRDX4 in AMs was 0.258±0.026, 0.214±0.012, 0.180±0.004, 0.165±0.008. The highest expression level was in the lung with dust group, and the lowest was in the silicosis with grade three group. The difference of the expression level of PRDX4 protein in AMs between groups was statistically significant ( P<0.05) . Conclusion:This experiment verified that PRDX4 expressed differentially in AMs in patients with silicosis. With the development of silicosis, PRDX4 expression in AMs reduced significantly.