Abstract: Oxidized rapeseed oil was sulfited by sodium bisulfite and neutralized by triethanolamine to obtain a vegetable oil-based fatliquoring agent (OSF-T). The low iodine value fatliquoring agent (OSF-PT) was then obtained by adding peracetic acid to remove residual sulfite. The two fatliquoring agents were applied to the fatliquoring experiment of cowhide wet blue, and their performance was compared with that of the commercial fatliquoring agent AMK. Results showed that both OSF-T and OSF-PT emulsions exhibited particle sizes ranging from 10 to 180 nm, which were smaller than that of AMK. Furthermore, OSF-T and OSF-PT exhibited excellent emulsion stability and dispersibility. Their fatliquoring performance was good. The softness of OSF-T fatliquored leather can reach 6.5 mm, and the content of volatile organic compounds (VOC) was 123.7 g/m². The VOC content of OSF-PT fatliquored leather was 121.3 g/m². The VOC contents of the above samples were lower than that of the commercial products (164.3 g/m²). The color of black OSF-PT fatliquored leather was lighter than that of AMK fatliquored leather, and the color difference (ΔE ) was 4.12. OSF-PT was more suitable for light leather fatliquoring. After thermal aging and ultraviolet aging treatments, the tensile strength of OSF-T fatliquored leather remained above 15 MPa, and the content of hexavalent chromium was less than 5 mg/kg. Fatliquoring agent OSF-T was slightly better than the commercial fatliquoring agent AMK in terms of softness, mechanical properties, aging resistance and hexavalent chromium content.