摘要： The exposure of poly(vinyl chloride) (PVC) materials to ultraviolet (UV) light can result in the destruction of the molecular structure and consequently a reduction of their mechanical properties. In this study, polybenzimidazole (OPBI) with panchromatic UV absorption was prepared by solution polycondensation and then used as a light stabilizer to improve the UV-resistance properties of PVC. PVC/OPBI composite films with different compositions were prepared by solution casting method, and the effects of OPBI content and UV irradiation time on the properties of these films were investigated by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, dynamic mechanical analysis and tensile test. The results show that OPBI has excellent UV absorption properties in the region of 220–420 nm and high thermal stability with a 3.0% weight loss at 550 °C in nitrogen atmosphere. The PVC/OPBI composite films also show excellent mechanical properties with a yield strength of 46.1–53.4 MPa, which can be attributed to the strong interactions among benzene rings, heterocyclic imidazole and chlorine atoms between OPBI and PVC. The special conjugated structure of OPBI allows the PVC/OPBI composite films to have high UV absorption and excellent mechanical properties, thus making it a promising light stabilizer.