The vegetable oil fatliquor (VF) was prepared by rapeseed oil, 1, 2-ethylenediamine and acrylic acid. The synthesis of a silicon modified vegetable oil fatliquor (SVF) was carried out using VF and polyether silicon by stirring and ultrasonic treatment. VF and SVF were measured by Fourier Transform Infrared Spectroscopy (FT-IR), thermogravimetry(TGA) and Transmission electron microscopy (TEM) respectively. SVF was applied in leather fatliquoring process, compared with product XQ-F3. The results indicated that polycondensation between hydroxy of polyether silicon and carboxylic hydroxy of VF occurred, the performance of VF could be improved by polyether silicon. The emulsifying surface tension of SVF decreased to 17.0 N/m, compared with 18.2 N/m of VF.The application results showed that the physical mechanical properties of leather fatliquored by SVF was equivalent to the leather fatliquored by industrial XQ-F3 fatliquor.