The ultraviolet radiation aging behaviors of PVC/CaCO3 and PVC/CaCO3/macromolecular modifier composites were studied through whiteness measurement, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and mechanical properties test. It was found that nano-CaCO3 particles used as ultraviolet light screening agents could significantly enhance the antiaging properties of PVC materials. Due to the macromolecular modifier coated on nano-CaCO3 particles, the compatibility of nano-CaCO3 and PVC matrix was improved, resulting in uniform dispersion of nano-CaCO3 in PVC matrix. Therefore, the PVC/CaCO3/MP composite exhibited better antiaging properties than PVC/CaCO3 composite. After 12 h of ultraviolet irradiation, the tensile strength retention, elongation at break retention, and impact strength retention of PVC/CaCO3/MP composite were 79.5%, 74.5%, and 75.3%, which were much higher than that of neat PVC and PVC/CaCO3 composite. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2749-2756, 2013