In this study, the poly (polyhedral oligomeric silsesquioxane-itaconic acid)〔P (POSS-IA)〕 nanocomposite material was prepared by free radical polymerization using octavinyl polyhedral oligomeric silsesquioxane (POSS-Vi) and itaconic acid (IA) as raw materials. The structure of POSS was characterized by FT-IR, 1H-NMR, XRD, and TEM. The POSS-Vi was uniformly dispersed in the polymer matrix with a diameter of about 50 nm. The P (POSS-IA) was applied to the tanning process of crust leather, and the properties of the tanning crust leather were compared with those of poly (itaconic acid)〔P (IA)〕, poly (acrylic acid)〔P (AA)〕, poly (polyhedral oligomeric silsesquioxane-acrylic acid)〔P (POSS-AA)〕, poly (methacrylic acid)〔P (MAA)〕, and poly (polyhedral oligomeric silsesquioxane-methacrylic acid)〔P (POSS-MAA)〕. The results showed that the shrinkage temperature of tanning crust leather with P (POSS-IA) was 68.2 ℃. The thickening rate of P (POSS-MAA) tanning crust leather was the highest, which can reach 53.3%. The tensile strength and tear strength of P(POSS-AA) tanning crust leather were the highest, reaching 31.6 MPa and 59.3 N/mm respectively. The results of SEM and EDS showed that P (POSS-IA) nanocomposite was more evenly dispersed.