〔Abstract〕 Objective To explore the effect of Wilms′ tumor 1-associated protein(WTAP) on tissue collagen deposition in pulmonary fibrosis caused by bleomycin. Methods 60 mice were randomly divided into four groups: control group(Control group), Bleomycin-induced pulmonary fibrosis group(BLM group), pulmonary fibrosis lentivirus empty vector control group(BLM+LV-NC group), pulmonary fibrosis WTAP lentivirus group virus group(BLM+LV-WTAP group). Experimental pulmonary fibrosis mouse model was established by subcutaneous injection of bleomycin(35 mg/kg) into the abdomen, twice a week for a total of 8 times. After modeling, Western Blot was used to detect the protein expression of fibrosis-related markers α-smooth muscle actin(α-SMA), type I collagen(Collagen Ⅰ), fibronectin(Fibronectin), and WTAP protein. Masson staining and Sirius Red staining were used to detect collagen deposition. RT-qPCR was used to detect WTAP mRNA expression, WTAP lentivirus infection effect, and Collagen Ⅰ mRNA expression. Results Compared with the Control group, the expression of pulmonary fibrosis markers α-SMA(P<0.001), Collagen Ⅰ(P<0.001), and Fibronectin(P<0.01) protein in the BLM group all increased. Masson staining(P<0.001) and Sirius Red staining(P<0.001) confirmed that significant collagen deposition occurred in the lung tissue of the BLM group. In addition, the expression of WTAP protein in the lung tissue of the BLM group increased(P<0.01). Compared with the Control group, the expression of WTAP mRNA in the BLM group increased(P<0.001). Compared with the BLM+LV-NC group, the expression of WTAP mRNA in the tissues of the BLM+LV-WTAP group decreased(P<0.001), proving that virus infection is effective. After infection with WTAP lentivirus, collagen fiber deposition decreased(P<0.001), Collagen Ⅰ mRNA(P<0.001) level decreased, and protein(P<0.001) expression decreased in the BLM+LV-WTAP group. Conclusion Knocking down of WTAP can reduce collagen deposition in bleomycin-induced pulmonary fibrosis tissue in mice and improve experimental pulmonary fibrosis.