Abstract: Semi-terminated isocyanate epoxy itaconate resin modified by silicone(IPDIHSiIE) was synthesized by graft copolymerization of polysiloxane modified epoxy itaconate resin(SiIE) that was prepared from the reaction between hydroterminated polysiloxane modified epoxy itaconic acid ester resin and half-terminated isocyanate. The chemical structure of IPDIHSiIE was characterized by FT-IR and ¹H NMR. Effects of the amount of polysiloxane on the physical and chemical properties of the modified resin and the film were investigated. The results showed that the reaction between polysiloxane and epoxy itaconate resin was completed at 90 ℃ for 8 h, indicating that the target product could be successfully prepared by silicohydride addition. With the increase of the amount of polysiloxane, the particle size of the modified resin dispersion gradually increased, the storage stability became worse, and the gel first risen and then fell. When the content of polysiloxane was 5%, the Z-mean particle size of aqueous dispersion was 129.8 nm, the aqueous dispersion was translucent and had no obvious change after storage for one month. Meanwhile, the gel rate reached the maximum of 93.1%. The hydrophobic property of the modified film was improved with the increase of polysiloxane content, and the film had good thermal stability. With the increase of polysiloxane content, the pencil hardness and flexibility of the film were improved, the adhesion decreased slightly and the glass transition temperature decreased gradually.