Phycocyanin (PC) is a light-harvesting protein isolated from Spirulina and has health benefits for a range of diseases including pulmonary fibrosis (PF). In this study, a bleomycin-induced pulmonary fibrosis model was used to determine whether PC attenuates PF and modulates the intestinal microbiota. The results showed that PC intervention attenuated the pulmonary fibrosis, demonstrated by hematoxylin-eosin staining (HE), Masson's trichrome staining, and lung dry-wet weight ratio, and PC significantly inhibited the production of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and lipopolysaccharide (LPS). Additionally, intestinal microbiota analysis revealed that PC intervention significantly increased the bacterial diversity and richness. Correlation analysis indicated that 9 families and 17 genes were significantly associated with at least 1 physiological index. And PC intervention significantly decreased the bacteria which is related to inflammation and dramatically increased the SCFAs-producing bacteria and probiotics. These data indicated that PC can decrease the pro-inflammatory cytokines and regulate the intestinal microbiota in BLM-induced PF mice.